Solemnity of the Most Holy Trinity

The name of the feast and its rank

The General Roman Calendar, promulgated in 1969 and taken up in the 2002 edition of the Missal, lists the feast on the "first Sunday after Pentecost" under the title of Solemnity of the Most Holy Trinity (Dominica prima post Pentecosten: Sanctissimae Trinitatis sollemnitas)^[6]. The liturgical calendar of the French-speaking countries gives it the rank of "Solemnity of the Lord" and the colour white^[7]. The Missal prescribes the Gloria and the Credo on that day, and the proper preface "of the mystery of the Most Holy Trinity"^[8].

Like all solemnities, the feast begins on the previous evening: "Solemnities are counted among the principal days, whose celebration begins with First Vespers, on the evening of the preceding day"^[9]. On the Saturday evening following Pentecost, the Liturgy of the Hours therefore already leaves the ordinary week for First Vespers of the Trinity^[10].

A feast that takes the place of a Sunday

In principle, Sunday never permanently admits another celebration: it is itself the "Day of the Lord", the Easter of every week, as the article Sunday explains. The norms of the calendar provide only four exceptions, and Trinity is one of them^[11]:

"Sunday by itself excludes the permanent assignment of another celebration. However: (a) on the Sunday within the octave of the Nativity of the Lord, the feast of the Holy Family is celebrated; (b) on the Sunday after 6 January, the feast of the Baptism of the Lord is celebrated; (c) on the Sunday after Pentecost, the Solemnity of the Holy Trinity is celebrated; (d) on the last Sunday in Ordinary Time, the Solemnity of Our Lord Jesus Christ, King of the Universe, is celebrated." — Universal Norms on the Liturgical Year and the Calendar, no. 6^[12]

The same text gives the reason for this reserve: "Sunday gives way to a celebration only to solemnities and feasts of the Lord" ^[13]. Trinity is therefore not a feast added to Sunday; it is Sunday itself which, on that day, says explicitly to whom all its praise is addressed. Liturgists have often stressed this link: Solesmes' L'Année liturgique recalled that the Sunday office is "specially consecrated to the Holy Trinity" ^[14], and the Micrologue, at the end of the 11th century, noted that the preface of the Trinity was already sung on Sundays^[15].

How is the date calculated?

The feast follows Pentecost by one week: it therefore falls fifty-six days after Easter, and its date moves with it. In the Gregorian calendar, it cannot be celebrated before 17 May nor after 20 June^[16]. It opens a short series of feasts which follow one another in the same order every year: on the following Thursday, the Solemnity of the Body and Blood of Christ, Corpus Christi, which is transferred to Sunday where it is not a holy day of obligation; then, on the Friday of the following week, that of the Sacred Heart of Jesus^[17].

The following table gives, for the next ten years, the date of Easter, of Pentecost, of Trinity and of the two solemnities that follow it; Corpus Christi appears both on Thursday and on Sunday, the date kept notably in France:

The last column shows that the same lectionary year returns every three years: the readings of the Mass, presented below, therefore change from one year to the next, while the prayers remain the same. For 2026, the date of 31 May, Corpus Christi transferred to Sunday 7 June and the Sacred Heart on Friday 12 June are confirmed by the official liturgical calendar of the dioceses of France^[18].

The threshold of Ordinary Time

Pentecost closes the fifty days of Eastertide. From the next day, the calendar resumes Ordinary Time, which "begins again on the Monday after Pentecost Sunday and ends before First Vespers of the First Sunday of Advent" ^[19]. Trinity is therefore the first Sunday of this second part of Ordinary Time, but its number disappears behind the solemnity: in 2026, Saturday 30 May still belonged to the eighth week of Ordinary Time and Thursday 4 June to the ninth, so that Trinity on 31 May took the place of the ninth Sunday^[20]. The article Ordinary Time describes this long season that thus opens.

This placement is no accident. After unfolding from Advent to Pentecost the great stages of Revelation, the Church embraces in a single gaze the one who revealed himself. Pope Benedict XVI said so at the Angelus on Trinity Sunday 2009:

"After Eastertide, whose culminating point was the feast of Pentecost, the liturgy provides for these three solemnities of the Lord: today, the Most Holy Trinity; next Thursday, the feast of Corpus Domini, Corpus Christi which, in many countries including Italy, will be celebrated next Sunday; and finally, the following Friday, the feast of the Sacred Heart of Jesus. Each of these liturgical feasts highlights a perspective from which the whole of the mystery of the Christian faith can be embraced." — Benedict XVI, Angelus of 7 June 2009, Solemnity of the Most Holy Trinity^[21]

The Ordinary Time that begins is therefore not a season without relief: it opens upon the mystery that gives meaning to all the others, God one and three, whose work the whole liturgical year, described in the article The Liturgical Year, unfolds.

A thousand years without a particular feast

In the early Church, "no office or particular day was assigned to the Holy Trinity", noted in 1912 the Catholic Encyclopedia article on Trinity Sunday^[22]. Solesmes' L'Année liturgique added that the feast, so naturally linked to Pentecost, had nevertheless come to be inscribed in the cycle of the year only "after long centuries" ^[23]. The reason for this delay is not forgetfulness: the Trinity needed no day, because it was the very form of all Christian prayer, from baptism to the "Glory be to the Father", as the section below on the meaning of the feast shows.

The Mass formularies later attached to the feast already existed, however. The preface of the Trinity, which confesses one God "not in the unity of a single person, but in the Trinity of a single substance", is found in the oldest books containing a Mass of the Trinity; at the end of the 11th century, the Micrologue attributed it, rightly or wrongly, to the authority of Pope Pelagius II, predecessor of Saint Gregory the Great, and specified that it was sung on Sundays^[24]. Hugues Ménard's 17th-century edition of the "Gregorian" sacramentary places this Mass on the octave of Pentecost, but its editor himself warns that this formulary "is not Gregorian": it therefore cannot be attributed to Saint Gregory^[25].

Around 800: Alcuin and the Mass of the Trinity

The first request for a Mass in honour of the Trinity in the Frankish liturgy goes back to a letter addressed around 775 to Charlemagne by a cleric named Cathwulf^[26]. The decisive step was taken some twenty years later by Alcuin (c. 735–804), the Anglo-Saxon scholar who became one of the masters of the Carolingian court and then abbot of Saint-Martin of Tours. He sent to the monks of Saint-Vaast in Arras and to those of Fulda Masses taken from his own missal, and the first of these Masses was dedicated to the Trinity^[27]:

"I have also drawn from our missal some Masses for the offices of each day and of the custom of the Church: first in honour of the sovereign Trinity; then to ask the intercession of the saints, and also to implore the help of the angels, so necessary to those who labour on this pilgrimage." — Alcuin, letter to the monks of Saint-Vaast in Arras, c. 796–804^[28]

In his letter to the monks of Fulda, dated 801–802, Alcuin explains that this small booklet will allow each one to pray "sometimes in honour of the Holy Trinity, sometimes for love of wisdom", for the tears of penitence, perfect charity or the help of the angels, according to the devotion of the day^[29]. The Mass of the Trinity was therefore first a votive Mass, which could be chosen on any day. Its distribution over the week, with Trinity fixed on Sunday, is not Alcuin's own, according to the work of the liturgist Jean Deshusses taken up by the historian Arthur Westwell^[30]; and Alcuin's exact share in the writing of these texts, whether as author or mere compiler, remains debated^[31]. In the 11th century, the Micrologue reported that Alcuin was said to have composed them "at the request of Saint Boniface", specifying that this was hearsay (ut aiunt); this is impossible, since Saint Boniface died in 754, nearly half a century before these consignments^[32].

This Mass nevertheless spread very quickly: it "very rapidly found its place in Benedictine missals", notes the historian Florence Close^[33]. Its collect, which gives thanks to God for having granted his servants "to acknowledge, by the confession of the true faith, the glory of the eternal Trinity, and to adore the Unity", was still that of the feast at the beginning of the 20th century, and the present Missal has taken up its central petition almost word for word^[34].

Stephen of Liège and the first office of the Trinity

A century later, the Mass received an office. Stephen, former canon of Metz who became bishop of Liège after 901 and died on 19 May 920, composed or gathered a complete office of the Trinity, with its responsories and antiphons for the night, the morning and the evening^[35]. The proof is a document from his successor, Bishop Richer, dated 16 November 932, which the canon Anselm of Liège copied in the 11th century into his chronicle of the bishops^[36]:

"Our predecessor, the venerable Stephen, took care to establish in honour of the Holy Trinity responsories with antiphons for nocturns or matins and for vespers, a whole complete office of a most sweet melody, convinced that it would be of great profit to him and to his Church to render specially the praises due to it." — Richer, bishop of Liège, mandate of 16 November 932, copied by Anselm of Liège, Gesta episcoporum, ch. 21^[37]

Richer adds that he had an oratory built in Saint-Lambert Cathedral, where Stephen rested, whose altar was dedicated to the Holy Trinity^[38]. Stephen's office is regarded as the oldest versified office composed and sung not in honour of a saint, but of God himself; its oldest copies date from the end of the 10th century, notably in Hartker's antiphoner at the abbey of Saint-Gall^[39]. It is this formulary, known by its opening words Gloria tibi Trinitas ("Glory to thee, Trinity"), which would be kept for the universal feast^[40].

L'Année liturgique affirmed in 1911 that Stephen had "solemnly instituted the feast" in his Church in 920^[41]. Recent research is more cautious. Florence Close has shown that no text speaks of such an intention: Stephen composed "the first votive office in the history of the liturgy", and "it is saying too much to affirm that he wished to institute a liturgical feast of the Trinity" ^[42]. The musicologist James Grier considers for his part that Stephen more probably reworked existing chants than created them^[43]. One fact remains: by giving the Trinity a whole office, Liège made possible the consecration of a day to this mystery, and that is indeed what the Churches which sang it at the octave of Pentecost did in the following century.

Rome's verdict: "every day, Glory be to the Father"

At the end of the 11th century, the usage had spread, but it remained contested. The Micrologue, a treatise on liturgical observances written between 1086 and 1100 by Bernold of Constance, calls the Sunday following Pentecost a "vacant Sunday" (Dominica vacans), without a formulary of its own, which simply takes up the office of Pentecost of which it is the octave^[44]. It judges the office of the Trinity "not authentic" and reports the answer of a Pope Alexander:

"Some institute the office of the Holy Trinity at the octave of Pentecost, although it is not marked with the alleluia, and even think it must be observed throughout the following week; but it is not authentic. […] That is why the pope Alexander, of pious memory, when questioned on this point, answered that, according to the Roman Ordo, no day should be specially assigned to the solemnity of the Holy Trinity, any more than to that of the Holy Unity, especially since every Sunday, and even every day, the memory of both is celebrated." — Bernold of Constance, Micrologue, ch. 60^[45]

This answer passed into the law of the Church. Gregory IX's Decretals reproduce it in their title "On feast days", in the form of a letter addressed to an archbishop who asked whether he could wear the pallium on Trinity day; the pope notes two customs there and gives the reason for the Roman reserve^[46]:

"According to the customs of the various regions, the feast of the Holy Trinity is celebrated by some at the octave of Pentecost, by others on the first Sunday before the Advent of the Lord. The Roman Church, for its part, has no usage of celebrating such a feast specially at any time of the year, since every day 'Glory be to the Father, and to the Son, and to the Holy Spirit' is said there, along with other similar formulas relating to the praise of the Trinity." — Decretal Quoniam in parte, Decretals of Gregory IX, book II, title 9, chapter 2^[47]

The Decretals attribute this text to Alexander III (1159–1181); but the Micrologue, written before 1100, already knew the answer of a "Pope Alexander", which pushes it back to Alexander II (1061–1073), as L'Année liturgique and the Catholic Encyclopedia hold^[48]. The pope condemned nothing: he did not forbid the feast where it existed — the title of the decretal specifies that "the custom of each Church is maintained" — but refused to make it an obligation, because the praise of the Trinity was daily^[49][50]. Other voices went further: according to the Liège historian Antoine Auda, the monk Pothon of Prüm rose up against those who introduced new feasts, beginning with that of the Trinity, and Sicard, bishop of Cremona, rejected it in turn^[51].

12th–13th century: the feast wins over the West

The devotion of the Churches nevertheless prevailed. At the beginning of the 12th century, the Benedictine abbot Rupert of Deutz, one of the great commentators of the liturgy, gave the reason the Church would retain:

"Immediately after celebrating the solemnity of the coming of the Holy Spirit, we sing the glory of the Holy Trinity in the Office of the Sunday that follows, and this arrangement is most fitting; for immediately after the descent of this divine Spirit began the preaching and the belief, and, in baptism, the faith and confession of the name of the Father, of the Son and of the Holy Spirit." — Rupert of Deutz, On the Divine Offices, book XI, ch. 1, translation from L'Année liturgique^[52]

At Cluny, the customs written by the monk Ulrich gave the feast no octave, but had the principal Mass of the Trinity sung throughout the week^[53]. In England, according to L'Année liturgique, Saint Thomas Becket instituted the feast in his Church of Canterbury in memory of his episcopal consecration, received in 1162 on the first Sunday after Pentecost^[54]; the Easter calculation for that year confirms that 3 June 1162, the day of his consecration, was indeed that Sunday^[55]. In 1222, the Carthusians received part of the office, which they would recite in full before 1582^[56].

The provincial council of Arles in 1260 made the feast a true solemnity, with an octave:

"Let the feast of the Holy Trinity be solemnly celebrated in the octave of Pentecost, from Vespers of the preceding Saturday and throughout the following week until Vespers of the following Saturday; let three lessons and three responsories be sung each day in their order, unless a feast of nine lessons occurs." — Council of Arles (1260), translation by Antoine Auda, 1923^[57]

Not all Churches chose the same Sunday. The decretal quoted above already knows the celebration on the Sunday before Advent, and L'Année liturgique points to Churches, such as Narbonne, Le Mans and Auxerre, which celebrated the Trinity twice, at the beginning and at the end of the series of Sundays after Pentecost^[58]. In the 13th century, according to the testimony of the liturgist William Durandus, bishop of Mende, the feast was celebrated in most Latin Churches^[59]; only Rome's decision was missing.

1334: John XXII extends it to the whole Church

The decision came from Pope John XXII, who resided in Avignon. He "ordered the feast for the whole Church on the first Sunday after Pentecost", summarises the Catholic Encyclopedia^[60]; Florence Close dates the adoption of the universal formulary to 1334, the last year of his pontificate^[61]. A new office had meanwhile been composed by the Franciscan John Peckham, Archbishop of Canterbury who died in 1292^[62]. L'Année liturgique saw in this decision the answer to a change in the calendar: the feasts of the saints were multiplying, and Sunday, the day of the Trinity, was increasingly giving way to them^[63]:

"It was therefore becoming necessary, in order to legitimise in some way this worship of the servants on the day consecrated to the sovereign Majesty, that at least once a year Sunday should offer the full and direct expression of that profound religion which the entire worship of Holy Church professes towards the sovereign Lord." — Solesmes' L'Année liturgique, "The Time after Pentecost", vol. I, 1911, p. 132^[64]

Alexander II's answer was not thereby contradicted: the feast was to add nothing to the daily praise, it was to make it visible. The Roman liturgical books continued moreover to count the Sundays "after Pentecost", and the Mass of the Trinity kept the trace of its origin there: at the beginning of the 20th century, the first Sunday after Pentecost was still commemorated in it, and the Gospel of that Sunday was read at the end of Mass in place of the prologue of Saint John^[65].

From Saint Pius X to today

The rank of the feast rose further. Long a double feast of the second class, it was raised by Saint Pius X, on 24 July 1911, to the rank of double of the first class "primary"^[66]. The 1969 calendar reform made it a solemnity, and Paul VI's Missal renewed its collect while keeping intact the preface that had been sung since Alcuin's time^[67].

This slow history does not say that the Trinity is a late discovery: it says on the contrary that the Church felt the need for a proper feast only when the daily praise of the Trinity risked becoming less visible. What had been everywhere since the origins then received a day.

The Mass of the solemnity

The Mass of the Trinity does not recount a scene from the Gospel: each of its prayers is a profession of faith addressed to the Father, through the Son, in the Spirit. The entrance antiphon sets the tone as soon as the priest enters: "Blest be God the Father, and the Only Begotten Son of God, and also the Holy Spirit, for he has shown us his merciful love" ^[68]. Then the Gloria is sung, followed by the collect, which the Liturgy of the Hours takes up at lauds and vespers of the same day^[69]:

"God our Father, who by sending into the world the Word of truth and the Spirit of sanctification made known to the human race your wondrous mystery, grant us, we pray, that in professing the true faith, we may acknowledge the Trinity of eternal glory and adore your Unity, powerful in majesty." — Collect of the Holy Trinity, liturgical translation of the Liturgy of the Hours^[70]

The prayer is built like the mystery it celebrates: the Father is named as the one who sends, the Word and the Spirit as those whom he sends, and the petition concerns the faith which acknowledges both the Trinity of Persons and the Unity of God. After the homily, the whole assembly proclaims the Credo, prescribed on that day as on every Sunday and solemnity^[71].

The summit of the Mass is the preface of the Holy Trinity, which the priest sings before the Sanctus. It is one of the oldest and densest of the whole Roman Missal:

"With your Only Begotten Son and the Holy Spirit you are one God, one Lord: not in the unity of a single person, but in the Trinity of a single substance. For what, by your revelation, we believe of your glory, we believe also of your Son and of the Holy Spirit, without any difference. So that, in confessing the true and eternal Godhead, we adore what is proper to the Persons, unity in essence, and equality in majesty." — Preface of the Holy Trinity, Roman Missal, literal translation from the Latin^[72]

In a few lines, the preface states the whole dogma which the Council of Nicaea and the First Council of Constantinople had defended: one God, three distinct Persons, equal in glory. This text was once sung on the ordinary Sundays of the year: the Micrologue already noted it in the 11th century, and this was still the usage of the Missal before the 1970 reform^[73][74]. The communion antiphon takes up Saint Paul: "As proof that you are children, God sent the Spirit of his Son into our hearts, crying out: Abba, Father!" (Gal 4:6)^[75]. The prayer after communion finally asks that "the reception of this sacrament and the confession of the holy eternal Trinity and of its undivided Unity" may profit us "for health of body and soul" ^[76].

A Mass spanning twelve centuries

These prayers were not born of the 20th-century liturgical reform. They are already read, almost word for word, in the "Holy Trinity" Mass of Alcuin's missal, around 800, as edited by the Patrologia Latina^[77]. The following table compares, prayer by prayer, this Carolingian Mass with that of the Roman Missal promulgated in 1970 and reissued in 2002:

We see that the feast instituted in the 14th century received a Mass already more than five hundred years old, and that the 1970 reform kept the essential of this treasure. The Church applies here the principle she has always followed: her way of praying expresses and guards her way of believing. The preface sung today confesses the Trinity with the very words used by the monks of Fulda and Arras to whom Alcuin wrote.

The Mass of the Trinity before 1970

The Missal in use before the 1970 reform gave the feast another face, described in 1911 by Solesmes' L'Année liturgique. The introit was not taken from Scripture: it was "a formula of glorification proper to this day" ^[78].

"May the holy Trinity and undivided Unity be blessed; let us praise it, for it has dealt with us in its mercy. O Lord our God, how admirable is your Name in all the earth!" — Introit Benedicta sit, Roman Missal before 1970, translation from L'Année liturgique^[79]

The collect was Alcuin's, already quoted; the epistle took up Saint Paul's hymn on the depth of God's wisdom (Rom 11:33–36); the Gospel was the missionary sending of Saint Matthew's ending (Mt 28:18–20), with the command to baptise in the name of the Father, and of the Son, and of the Holy Spirit^[80]. The same epistle is today the short reading of First Vespers, and the same Gospel that of Year B: from one missal to the other, the same founding texts are read on that day^[81][82].

L'Année liturgique also explained the choice of colour. The Church uses white "as a sign of joy, and to express the simplicity and purity of the divine essence" ^[83]. This is still the colour of the feast in the present Missal, which also prescribes it for the votive Mass of the Trinity^[84].

The readings of the Mass over three years

The Sunday lectionary, spread over three years (A, B and C), gives the solemnity three sets of readings which approach the mystery through three doors: the name of God revealed to Moses, the one God who lets himself be called "Father", the Wisdom who played before him prior to creation^[85]. The Gospel acclamation is the same each year and takes up the doxology the Church sings at the end of the psalms: "Glory to the Father, and to the Son, and to the Holy Spirit: to God who is, who was, and who is to come!" (cf. Rev 1:8)^[86].

The following table gives, for each year of the cycle, the exact references of the Mass readings in the liturgical translation used in French-speaking countries:

Thus none of the three years offers an "exposition" of the dogma: each lets us hear how God made himself known in history, from the cloud of Sinai to the sending of the disciples.

Year A: the name of God and the gift of the Son

The first reading of Year A recounts the theophany following the episode of the golden calf: Moses has gone back up the mountain with the stone tablets, and God passes before him proclaiming his name^[87].

"The Lord descended in the cloud and stood with Moses there, and proclaimed the name, THE LORD. The Lord passed before him, and proclaimed: 'THE LORD, THE LORD, a God merciful and gracious, slow to anger, and abounding in steadfast love and faithfulness.'" — Exodus 34:5–6, lectionary of the Holy Trinity, Year A^[88]

Instead of the psalm, the Church sings a fragment of the canticle of the three young men in the furnace (Dan 3:52–56), with the refrain "To you glory and praise for evermore!" ^[89]. The second reading is the conclusion of the Second Letter to the Corinthians, whose last verse has become one of the greetings of the Mass: "The grace of the Lord Jesus Christ and the love of God and the fellowship of the Holy Spirit be with you all" (2 Cor 13:13)^[90]. The Gospel, taken from Jesus' conversation with Nicodemus, says why the God revealed to Moses as "merciful and gracious" gave his Son:

"For God so loved the world that he gave his only Son, that whoever believes in him should not perish but have eternal life. For God sent the Son into the world, not to condemn the world, but that the world might be saved through him." — John 3:16–17, Gospel of the Holy Trinity, Year A^[91]

Year B: one God, whom we call Father

Year B opens on Israel's confession of faith: "Know therefore this day, and lay it to your heart, that the Lord is God in heaven above and on the earth beneath; there is no other" (Dt 4:39)^[92]. The feast of the Trinity never goes back on this monotheism: it receives it as it is, and the second reading shows how this one God lets himself be called "Father" by those whom the Spirit leads — "you have received the spirit of sonship; and by him we cry, 'Abba! Father!'" (Rom 8:15)^[93]. The Gospel is Saint Matthew's ending, where the risen Jesus names in one breath the Father, the Son and the Holy Spirit, in the formula of baptism:

"All authority in heaven and on earth has been given to me. Go therefore and make disciples of all nations, baptising them in the name of the Father and of the Son and of the Holy Spirit, teaching them to observe all that I have commanded you; and lo, I am with you always, to the close of the age." — Matthew 28:18–20, Gospel of the Holy Trinity, Year B^[94]

Year C: Wisdom, the Spirit of truth and hope

Year C lets us hear the personified Wisdom of the book of Proverbs: "Before the ages I was formed, from the beginning, before the earth was"; she stood beside the Creator, "playing before him at all times, playing in his inhabited world, and delighting in the sons of men" (Prov 8:23, 31)^[95]. Saint Paul then links the three Persons in a single sentence on hope: "hope does not disappoint us, because God's love has been poured into our hearts through the Holy Spirit which has been given to us" (Rom 5:5)^[96]. The Gospel, taken from the discourse after the Supper, shows the Spirit receiving from the Son what the Son receives from the Father:

"When the Spirit of truth comes, he will guide you into all the truth. […] All that the Father has is mine; therefore I said that he will take what is mine and declare it to you." — John 16:13, 15, Gospel of the Holy Trinity, Year C^[97]

The Trinity in the Liturgy of the Hours

The solemnity begins on Saturday evening, with First Vespers. Its short reading is Saint Paul's hymn which once served as the epistle of the feast's Mass: "O the depth of the riches and wisdom and knowledge of God! […] For from him and through him and to him are all things. To him be glory for ever. Amen" (Rom 11:33, 36)^[98]. At both Vespers, the antiphon of the Magnificat sums up in one sentence the whole economy of salvation:

"Mystery of the living God and of his love for men: the Most High sends us his Son and reveals himself our Father; Christ exalted in glory gives us his Spirit in whom we praise you, God who is, who was and who is to come!" — Liturgy of the Hours, antiphon of the Magnificat of First and Second Vespers of the Holy Trinity^[99]

The morning invitatory calls to adoration: "Let us adore our God, alleluia! Let us adore the Father, the Son and the Holy Spirit, alleluia!", and the antiphon of the canticle of Zechariah, at lauds, sings "the holy and one Trinity, who creates and governs all things now and for endless ages" ^[100]. The intercessions of lauds address in turn the Father, the Son and the Spirit: "Spirit of the Father and of the Son, bring your fruits to ripeness in our hearts: patience and gentleness, charity, joy and peace" ^[101].

The Office of Readings: Saint Athanasius' letter to Serapion

The Office of Readings combines two texts. The first is the passage from the First Letter to the Corinthians on "the mystery of God": "no one comprehends the thoughts of God except the Spirit of God" (1 Cor 2:11)^[102]. The second is a page from Saint Athanasius of Alexandria, the bishop who defended the faith of Nicaea against Arianism, taken from his letters to Serapion, bishop of Thmuis, on the divinity of the Holy Spirit. Athanasius starts from the tradition received from the Apostles to show that God's one action is always that of the three Persons:

"There is therefore a holy and perfect Trinity, acknowledged as God in the Father, the Son and the Holy Spirit; it contains nothing foreign, nothing mixed with it from outside; it is not made up of the Creator and the created, but it is wholly creative and productive power. It is like itself, indivisible by nature, and its activity is one. For the Father does all things through the Word in the Holy Spirit, and thus the unity of the Holy Trinity is preserved." — Saint Athanasius of Alexandria, Letter to Serapion, bishop of Thmuis, read at the Office of Readings of the Holy Trinity^[103]

The reading ends on Saint Paul's greeting which the Mass of Year A proclaims the same day: "the grace and the gift granted in the Trinity are given from the Father, through the Son, in the Holy Spirit" ^[104]. As on Sundays and feast days, the office concludes with the Te Deum, one stanza of which is a Trinitarian profession of faith: "You, O God, we praise: Father all-holy, eternal and well-beloved Son, Spirit of power and peace" ^[105].

The doctrine itself — one God in three equal and distinct Persons, the Son begotten, the Spirit who proceeds, the definitions of Nicaea and Constantinople — is set out in the article The Dogma of the Holy Trinity, and how to explain it in How Can the Trinity Be Explained Simply?. We attend here to what the liturgy makes of this mystery: why it devotes a Sunday to it, and how all its prayer confessed it long before the feast.

A feast with no event to commemorate

All the other solemnities of the Lord recall a fact that happened in time: the birth at Bethlehem, the Resurrection, the Ascension, the Spirit poured out on the fiftieth day. The feast of the Trinity commemorates no event; it contemplates God as he is before all creation. Solesmes' L'Année liturgique, the work of Dom Prosper Guéranger continued after his death by Dom Lucien Fromage, drew from this the explanation for the long delay in its institution^[106]:

"The ordinary reason for the institution of feasts was totally lacking here. A feast is the monument of a fact accomplished in time, whose memory and influence it is fitting to perpetuate: but from all eternity, before all creation, God lives and reigns, Father, Son and Holy Spirit." — Solesmes' L'Année liturgique, "The Time after Pentecost", vol. I, 14th ed., Paris-Poitiers, Oudin, 1911, p. 128^[107]

That is why the feast comes at the end of the great cycle running from Advent to Pentecost: the year has made known the Father who sends his Son, the Son who dies and rises, the Spirit who is given; on the following Sunday, the Church gathers these three revelations into a single adoration. The same work places it in the direct prolongation of Pentecost: the Apostles, "faithful to the Master's order, […] are about to set out to teach all nations, and to baptise men in the name of the Holy Trinity", and "it was therefore just that the solemnity whose aim is to honour God one in three persons should immediately follow that of Pentecost" ^[108]. The 1912 Catholic Encyclopedia article on Trinity Sunday says the same: it was after the first Pentecost that the doctrine of the Trinity was proclaimed to the world, and the feast therefore most fittingly follows that of Pentecost^[109].

A faith sung before it had its feast

The absence of a proper feast for a thousand years does not mean the Trinity was absent from prayer: it was its very form. The oldest manual of Christian life, the Didache (end of the 1st century), already prescribes baptism in the name of the three Persons, with the gesture of water poured three times^[110]:

"Concerning baptism, baptise thus: having first taught all these things, 'baptise in the name of the Father and of the Son and of the Holy Spirit', in running water. […] But if thou hast neither, pour water three times on the head, 'in the name of the Father and of the Son and of the Holy Spirit'." — Didache (Teaching of the Apostles), 7, 1.3^[111]

Around 155, Saint Justin describes to the Emperor Antoninus the celebration following baptism: the one presiding "offers up praise and glory to the Father of the universe, through the name of the Son and of the Holy Ghost", and gives thanks at length; the people answer Amen^[112]. In the next chapter, he sums up the Sunday prayer of the whole Church in one sentence: "In all our offerings, we bless the Creator of the universe through his Son Jesus Christ and through the Holy Spirit" ^[113].

The "Glory be to the Father" against Arianism

The doxology ending each psalm was born of the same confession. The oldest formulas gave glory to the Father through the Son in the Spirit; when the Arians leaned on these prepositions to make the Son and the Spirit inferior beings, the coordinate form "Glory be to the Father, and to the Son, and to the Holy Spirit" prevailed everywhere among Catholics in the 4th century^[114]. In 529, the Second Council of Vaison, in Provence, ordered that Gaul also add the sequel Sicut erat in principio ("as it was in the beginning"), which was said at Rome, in Africa and, it believed, in the East, in protest against Arianism^[115]. It is precisely this daily praise that Pope Alexander II invoked, in the 11th century, for not instituting a particular feast.

The liturgy, work of the Trinity

The Catechism of the Catholic Church opens its exposition of the liturgy with an article entitled "The liturgy, work of the Holy Trinity". Every blessing descends there from the Father through the Son in the Spirit, and every praise ascends by the same path^[116]:

"In the liturgy of the Church, the divine blessing is fully revealed and communicated: the Father is acknowledged and adored as the Source and the End of all the blessings of creation and salvation; in his Word, incarnate, dead and risen for us, he fills us with his blessings, and through him he pours into our hearts the Gift which contains all gifts: the Holy Spirit." — Catechism of the Catholic Church, no. 1082^[117]

Every Sunday Mass bears this form from beginning to end: it opens with the sign of the cross "in the name of the Father, and of the Son, and of the Holy Spirit", the Eucharistic prayer is addressed to the Father, makes memorial of the Son, invokes the Spirit upon the gifts, and ends with the great doxology rendering all glory to the Father through Christ, with him and in him, in the unity of the Holy Spirit; the people are finally blessed in the name of the three Persons^[118]. The feast of the Trinity therefore adds no new devotion: once a year, it makes visible the structure of all Christian prayer.

Baptism, entry into Trinitarian life

The Catechism begins its exposition of the mystery with baptism, not with a definition:

"Christians are baptised 'in the name of the Father and of the Son and of the Holy Spirit' (Mt 28:19). Before this they answer 'I believe' to the triple interrogation which asks them to confess their faith in the Father, the Son and the Spirit: 'The faith of all Christians rests on the Trinity'." — Catechism of the Catholic Church, no. 232, quoting Saint Caesarius of Arles^[119]

The Catechism specifies in the next paragraph that we are baptised "in the name" and not "in the names" of the three Persons, "for there is only one God" ^[120]. This is what the Gospel of Year B recalls, and what the sign of the cross repeats at every Mass, to which the article Why Do Catholics Make the Sign of the Cross? is devoted.

Indwelt by the Father, the Son and the Spirit

The feast looks not only to a distant God: it celebrates a God who comes to dwell in man. The Catechism makes this the end of the whole history of salvation:

"The ultimate end of the whole divine economy is the entry of God's creatures into the perfect unity of the Blessed Trinity (cf. Jn 17:21–23). But even now we are called to be a dwelling for the Most Holy Trinity: 'If a man loves me, says the Lord, he will keep my word, and my Father will love him, and we will come to him, and make our home with him' (Jn 14:23)." — Catechism of the Catholic Church, no. 260^[121]

The preceding paragraph draws the consequence for the life of each baptised person: "the whole Christian life is a communion with each of the divine persons, without in any way separating them. Everyone who glorifies the Father does so through the Son in the Holy Spirit; everyone who follows Christ does so because the Father draws him (cf. Jn 6:44) and the Spirit moves him (cf. Rom 8:14)" ^[122]. Following these lines, the Catechism quotes the prayer of a Carmelite of Dijon who had made this divine indwelling her whole life, Saint Elizabeth of the Trinity, presented below.

A Pentecost which is also the feast of the Trinity

The Catholic Encyclopedia article noted in 1912 that "the Greeks have no special feast" of the Trinity^[123]. This is correct if one looks for a distinct Sunday; but in the Byzantine rite, Pentecost itself is also the feast of the Trinity, hence its Russian name Troitsyn den, "the day of the Trinity", and the next day is dedicated to the Holy Spirit. The article Pentecost presents these usages, as well as the kneeling vespers; we note here only what the Byzantine liturgy sings of the Trinity on that day.

At Great Vespers on the eve, several songs of the lamp-lighting psalms are entirely Trinitarian. The first, sung twice, has become one of the best-known pieces of the Byzantine repertoire: "We have seen the true Light, we have received the heavenly Spirit, we have found the true faith, worshipping the undivided Trinity; it is she who has saved us" ^[124]. The hymn of glory concluding this series is attributed to the Byzantine emperor Leo VI the Wise, who died in 912, author of many liturgical hymns^[125]:

"Come, ye people, let us worship the Godhead in Three Hypostases, the Son in the Father, with the Holy Spirit; for the Father begat the Son co-eternal and sharing the same throne outside time, and the Holy Spirit was in the Father and glorified with the Son; one power, one essence, one Godhead, to which we say in adoration: Holy God, who created all things through the Son, in synergy with the Holy Spirit. Holy Mighty, through whom we have known the Father and the Holy Spirit came into the world; Holy Immortal, comforting Spirit, who proceedest from the Father and reposest in the Son: Holy Trinity, glory to thee!" — Leo VI the Wise, doxastikon of Great Vespers of Pentecost, Pentecostarion^[126]

The bilingual Slavonic-French edition giving this translation presents it as "the fullest exposition of the Orthodox teaching on the Holy Trinity found in the liturgical books" ^[127]. We recognise there, transposed into chant, the Trisagion ("Holy God, Holy Mighty, Holy Immortal") which each Person receives in turn.

"We have seen the true Light" at every liturgy

The first of these chants has overflowed Pentecost. In Russian usage, the choir sings it after communion at every Divine Liturgy of Saint John Chrysostom and Saint Basil, in response to the priest blessing the people, except during Eastertide^[128]. The Russian liturgist Alexei Dmitrievsky explained it in 1886:

"In our present liturgical practice the custom has been firmly established, at the liturgies of Basil the Great and John Chrysostom, for the choir to answer the priest's exclamation 'Save, O God, thy people' by singing the Pentecost sticheron 'We have seen the true Light'. Exception is made only for the whole of the Fifty Days." — Alexei Dmitrievsky, 1886^[129]

The same author specifies that this sticheron appears in the Russian celebrant's book only in the 17th century, and that Greek usage, more restricted, limited it to part of the year^[130]. Thus, for millions of Eastern faithful, every Eucharist ends on the confession of the "undivided Trinity" which saved the world: the feast of Pentecost has been prolonged through the whole year, much as the preface of the Trinity was, in the West, in the ordinary Sundays.

Andrei Rublev's icon of the Trinity

The most famous image of the Trinity was born of this Eastern piety. The monk and iconographer Andrei Rublev painted it for the Trinity Cathedral of the monastery founded by Saint Sergius of Radonezh, near Moscow, where it stood in the lower tier of the iconostasis and was venerated as miraculous. It entered Moscow's Tretyakov Gallery in 1929; in May 2023 it was handed back to the Russian Orthodox Church: displayed for a year at Moscow's Cathedral of Christ the Saviour, it has stood since June 2024 in the iconostasis of the Trinity Cathedral of the Lavra, its place of origin^[131]. Its date remains debated: some historians place it around 1412, others in the 1420s, in connection with the stone cathedral begun in 1422^[132]. A later Russian account of the holy iconographers, preserved in the painters' manuals, reports that Hegumen Nikon, Sergius' successor, had asked him to paint "the image of the Most Holy Trinity, in praise of his father, Saint Sergius the wonderworker" ^[133].

Rublev takes up the Genesis scene where Abraham receives three visitors under the oak of Mamre (Gen 18), which several Fathers, such as Saint Ambrose, read as a revelation of the Trinity in the Old Testament^[134]. But he removes Abraham, Sarah and the servant bringing the calf: only three angels remain seated around a table, before a chalice, with the house, the tree and the mountain in the background^[135]. Pope Francis evoked this image at the Angelus on Trinity Sunday 2023: "the table, which is at the same time an altar, is a symbol with which certain icons represent the Trinity. It is an image that speaks to us of a God of communion" ^[136].

The Russian Church gave this icon exceptional authority. In 1551, the Council of the Hundred Chapters (Stoglav), assembled in Moscow, was questioned on how to paint the Trinity and on the inscription to place near the angels. Its answer has remained famous^[137]:

"Let iconographers paint icons from the ancient models, as the Greek iconographers painted and as Andrei Rublev and the other renowned iconographers painted, and let them inscribe 'Holy Trinity', adding nothing of their own invention." — Council of the Hundred Chapters (Stoglav), Moscow, 1551, chapter 41^[138]

The Russian historian V. G. Bryusova warns against too broad a reading of this text: the council does not make Rublev the model of all icon art, it quotes him as the author of an image of the Trinity theologically irreproachable^[139]. Rublev was canonised by the local council of the Russian Orthodox Church assembled in 1988 for the millennium of the baptism of Russia^[140]. The articles Byzantine Icons and The Theology of the Icon place this work in the history and doctrine of the sacred image.

The "Throne of Grace", the image of the Trinity in the West

While the East contemplated the three angels of Mamre, the West forged its own image of the Trinity: God the Father, seated in majesty, holds before him the cross of his crucified Son, while the dove of the Spirit flies between their two faces. Art historians call it the Throne of Grace (in German Gnadenstuhl), after a word from Luther's Bible taken up in 1897 by the historian Franz Xaver Kraus; the expression comes from the Epistle to the Hebrews: "Let us then with confidence draw near to the throne of grace, that we may receive mercy" (Heb 4:16)^[141].

This type of image appeared in the 12th century and was, according to François Boespflug and Yolanta Zaluska, "for four centuries (13th–16th) the most popular of the images of the Trinity" ^[142]. It was born at the altar: the first Thrones of Grace adorn the canon page of the Mass, at the beginning of the Eucharistic prayer (Te igitur), as if the priest were offering the sacrifice of the Son to the Father in the Spirit^[143]. One of the oldest known, often held to be the first, appears around 1120 in a missal of Cambrai Cathedral, where the Father in majesty is surrounded by the symbols of the four evangelists^[144].

The type then reached great painting. In Florence, around 1425–1426, the young Masaccio painted in the Dominican church of Santa Maria Novella a fresco of the Trinity showing, at the top, the eternal Father, beneath him the dove of the Spirit, then Jesus crucified between the Virgin and Saint John, and, lower down, the two kneeling donors; the work, one of the first and most perfect examples of Renaissance perspective, ends with a skeleton lying down bearing this inscription: "I was once what you are, and what I am, you too shall be" ^[145]. In 1511, Albrecht Dürer painted for the chapel of a Nuremberg retirement home for elderly artisans, dedicated to the Holy Trinity and to all the saints, an altarpiece in which the Church of heaven and earth adores the Trinity represented as a Throne of Grace; the painting is now in Vienna's Museum of Art History^[146].

Which images of the Trinity does the Church allow?

Representing the invisible God raises a question the Church has not evaded. In the 18th century, images showing the Holy Spirit in the features of a handsome young man spread in Bavaria around the Franciscan tertiary Crescentia Höss of Kaufbeuren. The bishop of Augsburg had them removed, and Pope Benedict XIV, in a long letter dated 1 October 1745, upheld him and laid down the principle that still governs the question^[147]:

"Since it is not permitted to present to the eyes of men the image of a divine Person otherwise than in the form in which, according to the Holy Scriptures, that Person once made itself visible to men, it follows that it is permitted to paint the Holy Spirit on Pentecost day in the mystical figure of the tongues of fire descending upon the Apostles, or elsewhere in the appearance of a dove; but it is in no way permitted to depict him in the appearance of a youth or a man, since nowhere in the divine Scriptures is he found to have appeared to men in such a form." — Benedict XIV, letter Sollicitudini Nostrae to the bishop of Augsburg, 1 October 1745, § 22^[148]

The same document describes the "commonly approved" images: the Father in the form of an old man, after the "Ancient of Days" seen by the prophet Daniel (Dan 7:9), the Son on his breast and the dove between the two, or the Father and Christ side by side, separated by the dove^[149]. It recalls on the contrary that images of the Trinity in the form of a man with three faces had been judged monstrous by Saint Antoninus of Florence and Saint Robert Bellarmine, and that Pope Urban VIII, according to two authors quoted by Benedict XIV, had had some burned on 11 August 1628^[150]. As for the three angels received by Abraham, the pope admits they may have represented the Trinity, but refuses to draw from this a pretext for painting the Spirit alone in human form^[151].

The decision did not target Crescentia herself: the pope refused to settle the question of her role in spreading these images and referred it to a possible cause for beatification^[152]. She was canonised by John Paul II on 25 November 2001^[153]. The episode shows the Church's manner: she has never forbidden loving and representing the Trinity, she has only asked that the image say nothing other than Scripture.

The Holy Trinity columns of Central Europe

The Trinity also became a protectress of cities. In the South German and Austrian area, the great German dictionary of art history notes, she played a major role as protectress of communities, and that is why Trinity columns rose on town squares^[154]. In Vienna, Emperor Leopold I vowed to erect one during the plague epidemic of 1679; first in wood, the Graben column was rebuilt in marble from 1687 and consecrated on 29 October 1693, crowned with a group of the Holy Trinity^[155].

The most monumental stands at Olomouc, in Moravia. A stonemason of the town, Václav Render, submitted its design to the town council in early 1716, as the town was emerging from a plague epidemic; the works lasted from 1717 to 1754, and the column, about thirty-two metres high and containing a chapel in its base, was consecrated on 9 September 1754 in the presence of Empress Maria Theresa^[156]. UNESCO listed it in 2000 on the World Heritage List as "the most outstanding example of a type of monument specific to Central Europe" ^[157].

The Order of the Most Holy Trinity

The Trinity finally gave its name to a whole religious order devoted to charity. Founded by Saint John of Matha and approved by Pope Innocent III on 17 December 1198, the Order of the Most Holy Trinity and of Captives, the Trinitarians, devoted itself to ransoming Christians reduced to slavery, to which it consecrated a third of its revenues^[158]. Its motto, "Glory to thee, Trinity, and to captives liberty" (Gloria tibi Trinitas, et captivis libertas), begins with the very words opening the office of the feast: the praise of God one and three becomes there a work of liberation^[159][160].

The feast of the Trinity raises questions asked by Catholics and non-believers alike. The five most frequent concern its object, its date of appearance, the legitimacy of images and the difference between East and West. Each receives here an answer founded on the sources presented above.

Objection 1 — "A feast for an abstract idea?"

It is sometimes objected that the other feasts celebrate facts — a birth, a death, a resurrection — while this one celebrates a catechism formula, too abstract to touch life.

Answer: the feast does not celebrate an idea about God, but God himself, as he made himself known in those facts. That is why it comes at the end of the cycle running from Christmas to Pentecost: the Father who sends his Son, the Son who gives his life, the Spirit who is poured out are the very actors of the history the liturgical year has just recounted. Its readings contain moreover no theoretical exposition; they recount encounters, from Sinai to the mountain of Galilee.

This truth also touches the most concrete life. Benedict XVI drew from it, on the day of the feast, a consequence each one can verify: "The most eloquent proof that we are made in the image of the Trinity is this: only love makes us happy, for we live in relation, and we live to love and to be loved" ^[161]. A feast revealing that God is a communion of love tells man at the same time what he is made for.

Objection 2 — "Rome refused this feast for centuries: so it is a secondary devotion"

History seems to support the objection: in the 11th century, Pope Alexander II refused to introduce the feast at Rome, and the Micrologue judged it "not authentic".

Answer: the reason for the refusal says exactly the opposite of what the objection supposes. Rome had no proper day for the Trinity because she praised it every day by the "Glory be to the Father" and by other similar formulas^[162]. The reserve concerned the opportuneness of a particular day, not the mystery, and the decretal expressly maintained the customs of the Churches which already celebrated the Trinity^[163]. When John XXII extended the feast to the whole Church, it was to keep visible, amid ever more numerous feasts of saints, "the full and direct expression" of the adoration due to God alone^[164]. The feast is not an added devotion: it is the Church's daily praise made explicit one Sunday a year.

Objection 3 — "The Trinity is a late invention, like the feast itself"

A feast appearing in the Middle Ages would prove, it is said, that belief in the Trinity is itself a late construction of the Church, elaborated in the 4th century.

Answer: the date of a feast is not the date of a faith. Baptism in the name of the Father, of the Son and of the Holy Spirit is prescribed by the risen Christ himself (Mt 28:19), practised from the end of the 1st century according to the Didache, and the oldest description of the Mass, Saint Justin's around 155, gives glory to the Father of the universe through the name of the Son and of the Holy Spirit^[165][166]. What the 4th century made precise are the words to defend this faith against Arianism, and it was then that the doxology "Glory be to the Father, and to the Son, and to the Holy Spirit" prevailed^[167]. The article The Dogma of the Holy Trinity answers in detail the objection that the very word "Trinity" is absent from Scripture.

Objection 4 — "Can God be represented, when Scripture forbids it?"

The Old Testament forbids making images of God; painting the Father as an old man or the Spirit as a dove would therefore be a fault.

Answer: since the Son became man, the invisible God has made himself visible, and the Second Council of Nicaea, in 787, defended the veneration of images against the iconoclasts. For the Trinity itself, the Church laid down a precise rule: a divine Person is represented only in the form in which Scripture shows it making itself visible — the dove and the tongues of fire for the Spirit, Daniel's "Ancient of Days" for the Father, Abraham's three visitors for the Trinity — and images that invent, like the man with three faces or the Spirit in the features of a young man, are set aside^[168]. The article The Theology of the Icon sets out this foundation.

Objection 5 — "Why does the East have no Trinity Sunday?"

If the Eastern Churches do not know this feast, is this not the sign of a divergence of faith with the West?

Answer: the difference concerns the calendar, not the faith. The Byzantine rite celebrates the Trinity on Pentecost day itself, of which it is the other name, and its vespers rank among the richest Trinitarian professions of faith in all Christian liturgy^[169]. The West consecrated the following Sunday to the same confession. Both traditions thus say the same thing eight days apart: the Spirit given at Pentecost makes known the Father and the Son, and the whole Church adores the "undivided" Trinity which saved it.

Saint Augustine: "Lord God one, God Trinity"

At the end of the fifteen books of his treatise On the Trinity, composed over some twenty years, Saint Augustine refuses to conclude with a final argument: he ends the work with a prayer. He starts from the command to baptise in the name of the three Persons and from the "Hear, O Israel" proclaiming one God, then entrusts his whole inquiry to the one he sought^[170]:

"O Lord our God, we believe in thee, Father, Son and Holy Ghost. […] Directing my thought to this rule of faith, I have sought thee as far as I could; as far as thou hast given me power, I have desired to see with the eyes of the understanding what I believed; I have disputed much, I have laboured much, O Lord my God, my only hope, hear me; suffer not weariness to keep me from seeking thee; grant rather that I may ever seek thy face with ardour. […] O Lord God one, God Trinity, let thy faithful acknowledge whatever came from thee in these books; and if there is anything of my own, forgive it, thou and thine." — Saint Augustine, On the Trinity, XV, 28, 51^[171]

This prayer states the spirit of the feast: contemplation of the mystery is not a virtuoso exercise, it is a loving search ending in adoration.

Saint Catherine of Siena: "a deep sea"

Saint Catherine of Siena also ends her Dialogue, dictated in 1378, with a thanksgiving to the Trinity. The Church reads an extract of it each year at the Office of Readings of her feast, on 29 April^[172]:

"O eternal Godhead, O eternal Trinity, through the union of the divine nature thou hast given so great a price to the blood of thy only Son! Thou, eternal Trinity, art as a deep sea: the more I seek thee therein, the more I find thee; the more I find thee, the more I seek thee. Thou satisfiest our soul insatiably, for in thy abyss thou satisfiest the soul so that it remains needy and hungry, because it continues to wish and desire to see thee in thy light, O light, eternal Trinity." — Saint Catherine of Siena, Dialogue, ch. 167^[173]

Saint Thérèse of Lisieux: the offering of 9 June 1895

Trinity Sunday 1895 is a date in the history of holiness. On that day, at Lisieux, Saint Thérèse of the Child Jesus offered herself to Merciful Love, and the text of her offering, which she signed, bears the date of the feast^[174]. The text opens with an invocation to the Trinity:

"O my God! Most Blessed Trinity, I desire to love you and to make you loved, to work for the glorification of Holy Church by saving the souls on earth and [by] delivering those suffering in purgatory. I desire to fulfil your will perfectly and to reach the degree of glory you have prepared for me in your kingdom, in a word, I desire to be a saint, but I feel my helplessness and I ask you, O my God, to be yourself my holiness." — Saint Thérèse of Lisieux, Offering to Merciful Love, "feast of the Most Holy Trinity, 9 June in the year of grace 1895"^[175]

The "little way" lies whole in this page: counting on nothing of one's own strength, expecting all from Love. Thérèse offers to the "Blessed Trinity" the merits of Jesus, those of the saints and the love of the Virgin Mary, and she concludes by asking to renew this offering "at every beat of my heart" ^[176].

Saint Elizabeth of the Trinity: "O my God, Trinity whom I adore"

A Carmelite of Dijon, Elizabeth Catez (1880–1906), who entered Carmel under the name Elizabeth of the Trinity, made God's indwelling in the soul her whole life. Her prayer is so true that the Catechism of the Catholic Church quotes it following Christ's word: "we will come to him, and make our home with him" (Jn 14:23)^[177]:

"O my God, Trinity whom I adore, help me to forget myself entirely so as to be established in you, still and peaceful as if my soul were already in eternity; let nothing disturb my peace nor make me leave you, O my Unchanging One, but let each minute carry me further into the depth of your mystery! Pacify my soul. Make it your heaven, your beloved dwelling and the place of your rest." — Saint Elizabeth of the Trinity, prayer quoted by the Catechism of the Catholic Church, no. 260^[178]

She was canonised by Pope Francis on 16 October 2016, in Saint Peter's Square^[179]. Her prayer gives the feast its most intimate dimension: the Trinity the Church adores on the Sunday after Pentecost dwells, each day, in the soul that loves it.

In the writings of Luisa Piccarreta: one Will in three Persons

The Servant of God Luisa Piccarreta (1865–1947), a laywoman of Corato, in Apulia, recorded for forty years, in the thirty-six volumes of the Book of Heaven, what Jesus told her of the gift of "living in the Divine Will": no longer only doing what God wills, but letting God's will become the very life of the creature, as it was in the beginning^[180]. The Trinity often returns in these pages, and for a precise reason: the three divine Persons have but one will, and it is from them that the soul learns what living by a single will means.

No entry of the Book of Heaven mentions the feast itself, but one of them is dated Trinity Sunday 1927, 12 June. Luisa writes there that she was following the acts of the "divine Fiat" — the Fiat, that word by which God creates — "in order to repair and restore the relations between the Creator and the creature, the Redeemer and the redeemed, the Sanctifier and the sanctified". The answer she records runs through these three relations one after another: letting the Creator's will reign, studying the Redeemer's life, loving the Sanctifier^[181].

"And she who wants to know and receive all the bonds and relations of holiness must love the Sanctifier. The Holy Spirit lays his flames on the path of she who truly loves. He binds her with the relations of his Holiness. Without Love, there is no Holiness." — Jesus to Luisa Piccarreta, The Book of Heaven, vol. 22, 12 June 1927^[182]

The following year, 7 June 1928 — a Thursday, Corpus Christi day, four days after Trinity — another page explains how the human soul bears the imprint of the three Persons. It takes up an image Luisa had already noted in 1900, that of three suns whose rays blend so as to form but one^[183]:

"These three suns were formed by the Power of the Father, the Wisdom of the Son and the Love of the Holy Spirit. […] These three suns are the three powers: the intellect, the memory and the will. While distinct from one another, they hold one another by the hand and come to form a single power, symbol of our adorable Trinity. For while being Three distinct Persons, we form a single Power, a single Intellect and a single Will." — Jesus to Luisa Piccarreta, The Book of Heaven, vol. 24, 7 June 1928^[184]

A page from 1924 finally makes the Trinity the model of adoration. It joins what the Catechism teaches of the divine work — "just as it has but one and the same nature, the Trinity has but one and the same operation" ^[185] — and draws an invitation from it: to adore is to unite one's will to God's.

"If you desire to know the true and perfect model of adoration, come with me among the three divine Persons. […] See, my daughter, the first act of the divine Persons is the perfect Accord among their Wills. Our Wills are so united that the Will of one cannot be distinguished from that of the other. Even if our Persons are distinct — we are three — our Will is One." — Jesus to Luisa Piccarreta, The Book of Heaven, vol. 16, 13 May 1924^[186]

These pages add nothing to the sacraments: it is baptism, the Catechism recalls, which calls each Christian "to share in the life of the Blessed Trinity, here below in the obscurity of faith, and after death in eternal light" ^[187]. The Book of Heaven sees in it the end towards which this path leads — "whoever lives in my Will must rise to such heights as to come to live in the bosom of the Most Holy Trinity" ^[188] —: one will, God's, done on earth as in heaven.

The popes and Trinity Sunday

Each year, at the midday Angelus, the pope comments on the feast before the pilgrims gathered in Saint Peter's Square. In 2006, Benedict XVI took up an image from Saint Augustine to say what the Spirit discloses of God:

"Thanks to the Holy Spirit, who helps us understand the words of Jesus and leads us to the whole truth (cf. Jn 14:26; 16:13), believers can know, in a certain way, the intimacy of God himself, discovering that he is not infinite solitude, but communion of light and love, life given and received in an eternal dialogue between the Father and the Son in the Holy Spirit — Lover, Beloved and Love, to take up Saint Augustine." — Benedict XVI, Angelus of 11 June 2006, Solemnity of the Most Holy Trinity^[189]

He added that, "among all creatures, the Virgin Mary is the masterpiece of the Most Holy Trinity", because divine Love found in her a perfect answer and the Only Son became man in her womb^[190].

On 4 June 2023, Pope Francis started from a gesture learned in childhood: "As we trace the cross on our body, we remind ourselves how much God loved us, to the point of giving his life for us; and we repeat to ourselves that his love envelops us completely, from top to bottom, from left to right, like an embrace that never abandons us" ^[191]. Then he invited the whole square to make the sign of the cross with him, in the name of the Father, and of the Son, and of the Holy Spirit.

On Trinity Sunday 2026, 31 May, Pope Leo XIV commented on the Gospel of Nicodemus, who came to find Jesus by night. His meditation holds in one sentence, which the Church can make her own each year on that day:

"Dear friends, in the Mystery of God, Father, Son and Holy Spirit, we are at home, as Nicodemus felt at home near Jesus. The life of God is wonderful and captivating, it brings peace to our heart, often so restless, and makes us meet brothers and sisters in the joy of the Spirit. The Trinity makes us love all things and everyone: we discover that every creature is made for communion, for relationship, for encounter." — Leo XIV, Angelus of 31 May 2026, Solemnity of the Holy Trinity^[192]

And he concluded on the joy befitting that day: "Today, on the other hand, dear brothers and sisters, it is a feast! The feast of God is our feast" ^[193]. The highest mystery of the faith is not a riddle reserved for theologians: it is the house where each one is awaited, the one of which Christ promised: "we will come to him, and make our home with him" (Jn 14:23).

Related Ignispedia articles

• The Dogma of the Holy Trinity — the doctrine, its biblical foundations and the definitions of the councils
• How Can the Trinity Be Explained Simply? — good and bad analogies
• Pentecost — the feast preceding Trinity, and the Byzantine Pentecost
• Corpus Christi — the solemnity that follows, on Thursday or Sunday
• The Liturgical Year and Ordinary Time — the place of the feast in the Church's cycle
• Sunday — the Day of the Lord, which Trinity occupies once a year
• Why Do Catholics Make the Sign of the Cross? — the Trinitarian gesture of every day
• The Path of Mental Prayer: Going Deep to Meet the Triune God — the life of prayer as entry into the Trinity
• Saint Athanasius of Alexandria, Saint Augustine of Hippo, Saint Catherine of Siena, Saint Thérèse of Lisieux — the saints quoted in this article
• Saint John of Matha — the founder of the Order of the Most Holy Trinity
• Sergius of Radonezh, Byzantine Icons and The Theology of the Icon — around Rublev's icon
• Luisa Piccarreta and What Is the Gift of Living in the Divine Will?

Main sources

• Missale Romanum, editio typica tertia, Vatican City, 2002 (Mass of the Most Holy Trinity); Roman Lectionary and Liturgy of the Hours, liturgical translation of the AELF.
• Universal Norms on the Liturgical Year and the Calendar (1969), nos. 5, 6, 7, 11 and 44.
• Francis Mershman, "Trinity Sunday", The Catholic Encyclopedia, vol. XV, New York, 1912, p. 58.
• L'Année liturgique, by Dom Prosper Guéranger continued by Dom Lucien Fromage, "The Time after Pentecost", vol. I, 14th ed., Paris-Poitiers, Oudin, 1911, pp. 127–152.
• Florence Close, "L'office de la Trinité d'Étienne de Liège (901–920)", Revue belge de philologie et d'histoire 86 (2008), pp. 623–643.
• Antoine Auda, L'école musicale liégeoise au Xᵉ siècle. Étienne de Liège, Brussels, 1923.
• [Bernold of Constance], Micrologus de ecclesiasticis observationibus, Patrologia Latina, vol. 151, cols. 973–1022.
• François Boespflug and Yolanta Zaluska, "Le dogme trinitaire et l'essor de son iconographie en Occident", Cahiers de civilisation médiévale 37 (1994), pp. 181–240.
• Benedict XIV, letter Sollicitudini Nostrae, 1 October 1745, Bullarium, vol. I, Rome, 1746.
• Catechism of the Catholic Church, nos. 232–267 and 1077–1083.