Pope John XXI (c. 1210-1220 – 1277)

A physician and philosopher pope, according to tradition

The history of the Church includes theologian popes, jurist popes, monk popes, diplomat popes, and even soldier popes. It includes only one pope to whom tradition attributes a work as physician and logician: before he was John XXI, Peter of Spain — on the traditional hypothesis of a single identity — is said to have taught the arts and medicine, and to have written treatises on ophthalmology and pharmacology as well as a manual of reasoning read for centuries.^[16][17] On that same hypothesis, no other successor of Peter so united the university chair, the physician's practice, and the papal throne.

This singularity is not anecdotal. It illustrates a precise moment in the intellectual history of the West: the thirteenth century, when the massive entry of Aristotle and Greco-Arab science into the Latin universities produced a generation of scholars for whom faith and reason, theology and the natural sciences, were not enemies but allies. Peter of Spain belongs to the same Europe as Thomas Aquinas, Saint Bonaventure, and Albert the Great.

The only pope of his time in Dante's Paradise

Dante Alighieri was not gentle with the popes of his time. In the Divine Comedy, whose action is dated to Holy Week of the year 1300, he places several recent pontiffs in Hell — Nicholas III, already there, as well as Boniface VIII (died 1303) and Clement V (died 1314), whose damnation is announced by prophecy in canto XIX^[18] — or in Purgatory (Adrian V, canto XIX^[19]). Only one pope of his time enters Paradise: Peter of Spain, hailed in the Heaven of the Sun among the great doctors of Christendom — "the only pontiff of his time admitted by Dante to eternal beatitude," according to Domenico Consoli's notice.^[20][21] Dante also has Beatrice say that Gregory the Great, who had parted from Dionysius, "sì tosto come li occhi aperse / in questo ciel, di sé medesmo rise" (Paradise, XXVIII, 133-135), and he names in heaven the martyr popes Linus, Cletus, Sixtus, Pius, Callistus, and Urban (Paradise, XXVII, 40-45) and "il benedetto Agapito, che fue sommo pastore" (Paradise, VI, 16-18). But Dante celebrates Peter of Spain as a logician, not as a pontiff: he names him "Pietro Spano" and presents him as the one who "shines below in twelve little books" — a direct allusion to the twelve treatises of the Summulae traditionally attributed to the pope.

This detail lies at the heart of a scholarly debate explained below: the identification of Pope John XXI with the author of the Summulae Logicales, imposed from the mid-fourteenth century onward, is now debated by medievalists.^[22][23]

A death that became famous

Few papal deaths have struck the imagination as much as that of John XXI. A learned pope crushed by the fall of part of his apartment — a chamber he had had built to study in peace, according to a late tradition: the image had something tragic and enigmatic about it. Chroniclers saw in it a sign, some a punishment, others proof that he was involved in occult sciences.^[24][25] This black legend of the magician pope, born from his learning and studious solitude, long accompanied his memory.

A Portuguese birth with uncertain dates

Pedro Julião was born in Lisbon; according to another tradition, his name may come from the parish of Saint Julian where he is said to have been born. The Catholic Encyclopedia and Treccani place his birth between 1210 and 1220; no precise date is established.^[26][27] He was, says the Catholic Encyclopedia, "son of a certain Julianus, baptized Peter, and known under the name of Petrus Juliani or Petrus Hispanus."^[28]

Known to learned Europe as Petrus Hispanus, "Peter of Spain," Peter was Portuguese — the only Portuguese pope in history, according to the Columbia Encyclopedia.^[29]

Studies in Paris

Like many brilliant minds from the peninsula, the young Peter came to Paris, then the intellectual capital of Christendom. Treccani notes that it is unanimously accepted that he obtained there the title of magister, despite the complete absence of sources on his academic career; the exact dates remain conjectural, around the 1230s-1240s.^[30][31] The Catholic Encyclopedia reports that he there heard Albert the Great lecture on Aristotle's physics and metaphysics; Treccani, which does not name Albert, invites retaining this tradition only with caution, for lack of sources.^[32][33]

It was in the Parisian university milieu, amid the assimilation of the Aristotelian corpus, that the logician and philosopher of nature was formed.

The master of medicine

After Paris, a Peter of Spain remembered as a physician — traditionally identified with the future pope — turned to medicine. The Catholic Encyclopedia states that he was called as early as 1247 to teach medicine at the University of Siena.^[34] The Sienese documents do name a "maestro Pietro medico, detto Ispano" (acts of 1245, 1248, and 1250), but the uncertainty concerns the identity of this physician with the future pope: after 1250, the dozens of documents marking Pedro Juliao's ecclesiastical career always call him maestro and never medico, and no certain link can be established between the physician-writer Peter of Spain and the ecclesiastic Peter of Spain.^[35]

His most famous medical writings, beginning with the Thesaurus Pauperum, belong to this period.

Dean of Lisbon, archbishop-elect of Braga

The scholar was also a cleric who climbed the ranks of the hierarchy. Around mid-century, Peter was dean of Lisbon and connected to the chapter of Braga, the great primatial see of Portugal.^[36][37] In 1272 (in May, by unanimous vote of the chapter, without pontifical confirmation), he was elected archbishop of Braga — a dignity he would scarcely exercise, since his destiny was already drawing him toward Rome.^[38][39][40]

Cardinal-bishop of Tusculum (1273)

The decisive turning point came from Pope Gregory X, one of the great reforming pontiffs of the century and organizer of the Second Council of Lyon. On 3 June 1273, Gregory X created Peter of Spain cardinal-bishop of Tusculum (Frascati), one of the most prestigious suburbicarian sees of the Sacred College.^[41][42] Tradition also reports that he was Gregory X's personal physician; Treccani notes, however, that no document records him in that function, which should be regarded as plausible but unproven.^[43]

Within three years, this Portuguese cardinal would be carried to the summit of the Church.

The Summulae Logicales, Europe's textbook

The most influential work attributed to Peter of Spain is a logic manual known under the title Tractatus, later renamed Summulae Logicales ("little summaries of logic"). According to the Catholic Encyclopedia, it was for "almost three hundred years the favourite textbook on logic" in the Latin universities.^[44] Its diffusion was without equal: the Stanford Encyclopedia of Philosophy notes that "the great number of manuscripts and printed editions" bears witness to the enormous success it enjoyed in European universities until the seventeenth century.^[45]

The standard critical edition is that of the Dutch medievalist Lambertus Marie de Rijk (1972), who established the Latin text from the manuscripts.^[46]

The parva logicalia and the logic of terms

The Tractatus consists of twelve treatises (libelli). The first present the classical logic inherited from Aristotle — notions, categories, propositions, syllogism, and dialectical topics. But the originality of the work lies in the semantic treatises that tradition called the parva logicalia ("little logics"): suppositions, ampliations, appellations, restrictions, distributions, and relatives (treatise VIII, De relativis).^[47] These treatises analyze how the same term changes its signification according to its context in a proposition — for example, how "man" can designate the species, an individual, or all individuals. It is one of the peaks of medieval terminist logic, anticipating questions that remain alive in philosophy of language.

Barbara, Celarent: the memory of the syllogism

The tradition of the Summulae remains associated with one of the most durable pedagogical inventions of logic: the mnemonic verses Barbara, Celarent, Darii, Ferio, which help students remember the valid modes of syllogism — the Catholic Encyclopedia notes that they "occur in the work."^[48] Each word encodes, through its vowels, the form of the propositions in a valid argument. Their exact authorship is debated — the book draws, in substance and form, on the Parisian method and on the compendium of the English logician William of Sherwood^[49] — but they are inseparable from the success of the Summulae.

The Thesaurus Pauperum and the medical writings

To the physician, tradition attributes the Thesaurus Pauperum ("Treasury of the Poor"), a collection of accessible remedies "for the diseases of every part of the body," ordered "from the hair to the toenails."^[50][51] Besides the Thesaurus, the Peter of Spain of the pontifical tradition is reputed to be the author of fourteen other medical writings^[52]; he is also credited with an ophthalmological treatise, the Liber de oculo ("On the Eye") — edited and translated by A. M. Berger (Munich, 1899)^[53]. The Thesaurus Pauperum benefits from the critical edition of the Portuguese philologist Maria Helena da Rocha Pereira.^[54][55] It circulated, like the Summulae, widely and was copied, translated, and printed for centuries.

The commentary on the soul and Aristotle

The philosopher of nature completes the logician and the physician. Peter of Spain is credited with a Scientia libri de anima ("science of the book on the soul"), commentaries on Aristotle - the De anima, the De morte et vita, and the De sensu et sensato - as well as writings inspired by the Christian Neoplatonist Pseudo-Dionysius and a collection of sermons.^[56][57] Together they draw the portrait of a complete scholar, standing at the meeting point of medicine, natural philosophy, and theology.

The question of attribution

This is the most disputed point in the dossier. For centuries, it was taken for granted that Pope John XXI, the logician of the Summulae, the physician of the Thesaurus, and the commentator on Aristotle were one and the same man. This identification structured the whole history of medieval philosophy.^[58][59]

Modern research has challenged it. The Spanish logician and medievalist Ángel d'Ors (1951-2012, catedrático de Lógica at the Complutense in Madrid), in a series of studies published in Vivarium between 1997 and 2003, argued that the author of the Summulae should be sought in the Dominican order rather than on the throne of Peter.^[60] The Stanford Encyclopedia of Philosophy reports that an earlier tradition already made the author a Spanish Dominican, and that a fifteenth-century attribution targeted Petrus Ferrandi Hispanus; it adds that recent research has taken up the Dominican hypothesis (D'Ors 1997, 2001, 2003), while specifying that several of the Dominican candidates proposed can now be ruled out (Tugwell 1999, 2006).^[61] The large manuscript repertory compiled by the Portuguese medievalist José Francisco Meirinhos confirmed the complexity of the corpus gathered under the name "Peter of Spain," which may cover several distinct authors.^[62] The Stanford Encyclopedia of Philosophy summarizes the situation frankly:

"However, we are still in the dark about the true identity of Peter of Spain." — Stanford Encyclopedia of Philosophy, The Logic of Peter of Spain^[63]

What should be retained? That the traditional identification — a pope unique in kind, physician, logician, and philosopher — imposed itself from the mid-fourteenth century onward and remains the received reading, but that it is now debated by medievalists. John XXI remains the pope to whom tradition, since the fourteenth century, attributes this immense work, without the link between the churchman and the author of the Summulae being established with certainty.

Ubi periculum and the cardinals' revolt

To understand John XXI's election, one must return to his protector, Gregory X. Elected in 1271 after a conclave that had lasted almost three years - the longest in history - Gregory X wanted to make such a scandal impossible in the future. At the Second Council of Lyon (1274), he promulgated the constitution Ubi periculum, which imposed a strict enclosure on the cardinals after a pope's death: locked together, deprived of communication with the outside world, and subjected to a progressive rationing of food until they elected.^[64][65] This was the birth certificate of the modern conclave (from the Latin cum clave, "with a key").

These harsh rules were very badly received by the cardinals, who never stopped trying to free themselves from them.

The year of four popes

The year 1276 is one of the most extraordinary in papal history: four popes succeeded one another. The table below summarizes this dizzying cascade; each row refers to the pontiff's notice and its sources.

Adrian V, dead within a few weeks, had had time to suspend Ubi periculum without replacing it with any new rule, leaving a legal void. It was in this unsettled context that the conclave met once again at Viterbo.^[71][72]

The conclave of Viterbo and the election

Meeting in the episcopal palace of Viterbo, the conclave chose the Portuguese cardinal Peter of Spain. The exact date of the election is debated: Salvador Miranda's cardinals repertory gives 8 September 1276, the Catholic Encyclopedia places it "in the week following 13 September," while Treccani (as probable) and the Holy See's official list give 16 September 1276.^{[73][74][75][76]} All sources agree, however, on the date of the coronation: 20 September 1276, in the cathedral of San Lorenzo in Viterbo, by Cardinal Giovanni Gaetano Orsini.^[77][78][79]

The new pope chose the name John - a name carrying a curious history of numbering, to which we will return.

The suspension of the conclave rules

John XXI's first major act of government was to suspend the legacy of Ubi periculum. By the bull Licet felicis recordationis, he put in writing the verbal suspension already pronounced by Adrian V and announced that he wished to rewrite the constitution — a promised reform that his unexpected death prevented.^[80] The Catholic Encyclopedia specifies that in ratifying his predecessor's decision, he "suspended, with the consent of the cardinals, the decrees issued at Lyons, and declared his intention of issuing in the near future the new regulations."^[81]

The decision restored freedom to the cardinals — but it had a perverse effect: without enforced enclosure, conclaves again became long and exposed to political pressure. It would not be until 1294 and Pope Celestine V that the conclave rules were restored — a text taken up in the Decretals (bk. I, tit. VI, ch. 3)^[82] — that is, eighteen years later. On this point, John XXI's work was therefore, institutionally, a regression that history took nearly two decades to correct.

A government dominated by Cardinal Orsini?

Several decades after the pope's death, Tolomeo da Lucca (Ptolemy of Lucca) wrote in his Historia ecclesiastica that the principal architect of Peter of Spain's election, and then the holder of the direction of the curia, was Cardinal Giovanni Gaetano Orsini, the future pope Nicholas III.^[83] This passage of Tolomeo seems to be the single source on which the often-repeated accusation of governmental incapacity is based. Yet Tolomeo is among the Dominican chroniclers — Martino Polono, Jacopo da Varazze, Francesco Pipino, Bernard Gui — whose biting judgments on the pope and his incapacity for government Treccani notes: perhaps because they considered themselves struck by the condemnations of 1277, or because the pope had not protected them.^[84] Conversely, the pontifical register stresses the diplomatic ability with which the pope conducted his policies, and the Catholic Encyclopedia merely notes that Cardinal Orsini "exercised a great influence on the government of the Church."^[85]

The union with the Greeks

The great ecclesial dossier of the moment was the union of the Churches. At the Second Council of Lyon (1274), the Byzantine emperor Michael VIII Palaiologos had had his ambassadors accept the reunion of the Greek Church with Rome and the recognition of Roman primacy.^[86] John XXI pursued this policy: he confirmed for Constantinople the nuncios already chosen by Innocent V — two bishops and two Dominicans, prevented from leaving by that pope's death and the brevity of Adrian V's pontificate — in order to consolidate the still fragile union.^[87][88] In April 1277, a synod assembled at Constantinople approved the profession of faith and recognized Roman primacy; but the professions of faith and the emperor's documents, entrusted to a messenger, reached Viterbo only after the pope's death.^[89][90] The union of Lyon would not long survive the death of its promoters, but John XXI was, briefly, one of its guardians.

The crusade project and the missions

Like all popes of his century, John XXI dreamed of recovering the Holy Land. He worked to organize a crusade and to pacify Christian princes so that their forces might be freed. The Catholic Encyclopedia reports that he "designated missionaries to go to the Tartars, but died before they set out."^[91] The missionary project toward the Mongol East, sketched by other pontiffs of the century, remained a dead letter for lack of time.

Arbitration among princes

The pope also tried to keep the balance among the great powers. Treccani notes the submission of Charles of Anjou, king of Sicily, on 7 October 1276, the cautious dealings with Rudolf I of Habsburg concerning the imperial coronation, and an attempt at mediation between France and Castile under Alfonso X.^[92] On all these fronts, the pontificate was too short to produce lasting results.

It was through an indirect act that John XXI left his deepest mark on the history of ideas. Himself a scholar, he was alerted to philosophical doctrines judged dangerous that were spreading at the University of Paris, especially under the influence of Aristotle read through his Arab commentator Averroes.

The letter Relatio nimis implacida

On 18 January 1277, by a letter beginning with the words Relatio nimis implacida ("a report too little appeasing"), John XXI informed the bishop of Paris Stephen Tempier of rumors of heretical errors circulating in his diocese, and charged him with investigating the origin and authors of these doctrines.^[93][94]

Stephen Tempier's 219 theses

Tempier went further than the pope had asked. On 7 March 1277, without waiting for a new Roman instruction, he published a syllabus of 219 condemned propositions, striking with excommunication anyone who upheld them or even listened to them.^[95] Tempier named no target: he aimed at unspecified members of the Paris arts faculty, accused of professing a radical Aristotelianism — eternity of the world, unity of the intellect, autonomy of philosophical reason before faith.^[96] Their names appear nowhere in the document itself, except in the rubrics of two of the many medieval manuscripts that preserved it; Siger of Brabant and Boethius of Dacia only subsequently became the principal target of the condemnation.^[97][98] The standard critical inquiry by Roland Hissette traced the Parisian sources of these articles one by one: of the 219 propositions, only 79 can be identified, with various degrees of probability, in the works of Siger, of Boethius, or of three anonymous writings; for 72 propositions the attribution is uncertain, and 68 could not be identified at all.^[99][100]

According to the Stanford Encyclopedia of Philosophy, Tempier's intervention of 7 March 1277 is the best known in the philosophical historiography.^[101]

What did the pope really want?

John XXI triggered the inquiry, but did not draft or directly approve the list of 219 theses, which was Tempier's own work with a commission of Parisian theologians.^[102][103] The pope died less than three months after the condemnation, without being able to measure its scope. The historian of science Pierre Duhem lent this condemnation an immense scope: by forbidding certain theses on divine omnipotence and the necessity of the world, it is said to have paradoxically freed thought from the overly rigid presuppositions of one form of Aristotelianism and opened the path toward modern science — a thesis taken up with nuances by Edward Grant, but contested, notably by Alexandre Koyré.^[104] No one in the field, however, any longer retains 1277 as the birth of modern science.^[105]

The attentive reader has already noticed the anomaly: there has never been a Pope John XX. The list passes directly from John XIX (dead in 1032) to John XXI (1276). Treccani sums it up plainly: "through a calculation error, there has never existed a Pope John XX," and the Catholic Encyclopedia even titles its article "Pope John XXI (XX)," indicating that he would "really" be the twentieth.^[106][107]

The confusion of Marianus Scotus

The generally accepted explanation lies in a confusion in the writings of Marianus Scotus (eleventh-century chronicler): copied by later authors, it inserted into the catalogues a ghost "John" — a four-month pontificate between Boniface VII (d. 985) and John XV — and shifted the whole following numbering.^[108] Upon ascending the throne, Pedro Julião took this count for granted: he skipped the number XX and called himself John XXI.^[109][110]

Neither Pope Joan nor a mystery

A tenacious legend attributes the absence of John XX to the famous Pope Joan, who supposedly reigned secretly between two popes. This is false: Pope Joan is herself a medieval fable^[111], and the numbering anomaly is explained by an error of calculation and transmission.^[112] The skipped number XX is an accident of erudition, not a hidden secret.

The collapsed apartment

On 14 May 1277, while the pope was alone in the papal apartment at Viterbo, a roof — or part of the apartment — collapsed. According to a late tradition, earlier than the end of the fifteenth century and absent from the oldest sources, the pope had had a dependency of the palace built there in order to withdraw and study in solitude. The Catholic Encyclopedia recounts the scene soberly:

"On 14 May, 1277, while the pope was alone in this apartment, it collapsed; John was buried beneath the ruins and died on 20 May in consequence of the serious injuries he had received."

• Catholic Encyclopedia, article Pope John XXI (XX)^[113]

Pulled alive from the debris but gravely injured, the pope survived six days and died on 20 May 1277.^[114][115] The date of death, 20 May, is solidly established by the same two sources.

The black legend of the magician pope

The death of a learned pope amid his books left a deep impression. Unable to understand his scientific research and his taste for solitude, a few monastic chroniclers, "regarding him as an enemy," spread the accusation that he practiced the magical arts.^[116] The Catholic Encyclopedia calls these stories "baseless tales."^[117] Treccani observes that the German writers and above all the Dominicans were hostile to him — perhaps because they considered themselves struck by the condemnations of 1277, or because the pope had not protected them.^[118] The reputation of the "magician pope" was thus forged by hostile chroniclers.

Burial and memory

John XXI was buried in the cathedral of San Lorenzo in Viterbo, where he had been crowned about eight months earlier.^[119][120] His tomb is still there. The memory of the Church retained from him not the man of government — his pontificate was too brief for that — but the scholar whom all Europe had read according to tradition.

The most dazzling homage paid to Peter of Spain comes from a man who had little love for popes: Dante Alighieri. In the Heaven of the Sun, sphere of the great theologians and scholars, the soul of Saint Bonaventure lists the luminous spirits around him - and names among them "Pietro Spano." In the body of the text, the English reader may read:

"Hugh of Saint Victor is here with them, and Peter Comestor and Peter of Spain, who shines below in twelve little books." (literal translation) — Dante, Paradise, canto XII, lines 133-135^[121]

The "twelve little books" (dodici libelli) are a clear allusion to the twelve treatises of the Summulae Logicales.^[122][123] Dante here praises the logician Pietro Spano, and the identification of that logician with Pope John XXI is precisely what modern criticism questions: the old commentators, without exception, say nothing of the pontifical dignity of this figure, which Dante himself passes over in silence.^{[124][125][126]} Still, this identification earned John XXI a unique place in the memory of Christendom.

Reference sources

• Treccani, Enciclopedia dei Papi, "Giovanni XXI" (notice by José Francisco Meirinhos, 2000) - the most recent and cautious scholarly synthesis on the disputed biographical data.^[127]
• Catholic Encyclopedia (New Advent), "Pope John XXI (XX)" (1910) - the classic factual framework, to be compared with recent research.^[128]
• Encyclopaedia Britannica, "John XXI" - synthetic notice on his life and works.^[129]
• Treccani, Enciclopedia Dantesca, "Giovanni XXI papa" - on the presence of Peter of Spain in Dante's Paradise.^[130]

On the logical work and its attribution

On the context of the pontificate

• Stanford Encyclopedia of Philosophy, Condemnation of 1277 - on the letter Relatio nimis implacida and Tempier's 219 theses.^[131]
• Roland Hissette, Enquête sur les 219 articles condamnés à Paris le 7 mars 1277, Louvain, 1977 - the standard critical analysis, article by article, of Tempier's syllabus.^[132]
• Second Council of Lyon (1274) - on the constitution Ubi periculum and the union with the Greeks under Michael VIII Palaiologos.^[133]

• Pope Gregory X (1271-1276) — Peter of Spain's protector, author of the conclave rules that John XXI suspended.
• The Second Council of Lyon (1274) — the union with the Greeks and the constitution Ubi periculum.
• Pope Nicholas III (1277-1280) — Cardinal Orsini, presented by a single source as the strong man of John XXI's pontificate, who succeeded him.
• Pope Urban IV (1261-1264) — another thirteenth-century pope elected at Viterbo.
• Saint Thomas Aquinas — contemporary of Peter of Spain, dead in 1274 on the road to the Council of Lyon.