Pope Leo XIII (1810-1903)

The pontificate of Leo XIII marks a change of method in the history of the contemporary papacy. His predecessor Pius IX had fought a frontal battle against liberalism, the secular State and political modernity: the Syllabus of 1864 condemned the errors of the century as a whole, and the fall of Rome in 1870 had sealed an apparently total rupture between the Holy See and the world born of the Revolution.^[10] Leo XIII inherited this situation of isolation.

His own contribution was to join to this doctrinal firmness a strategy of occupying the ground: without subtracting anything from dogma — he reaffirms the teaching of Pius IX, condemns Freemasonry, defends the rights of the Church — he brings the Church onto the intellectual, social and diplomatic ground through doctrine and dialogue. This is the spirit of his whole reign.^[11]

The direction of the reign was one of rapprochement: drawing the Church out of purely defensive positions to place her again at the heart of the great debates of her time.^[12]

This policy of measured openness unfolded on three fronts. On the intellectual front, the pope relaunched the philosophy of Saint Thomas to give Catholics a solid reason with which to answer positivism and materialism. On the social front, he took seriously the workers' question, still little treated by the magisterium, and traced a path of his own that is neither liberalism nor socialism — not a competing economic system, a “third way,” but the moral principles of a teaching rooted in Catholic Tradition and developed for modern times.^[13] On the diplomatic front, he drew the papacy out of its isolation by renewing relations with Germany, France, Russia and even Protestant powers.^[14][15]

To understand Leo XIII is to grasp this unique line: a pope doctrinally uncompromising and pastorally daring, who believed that Catholic truth had nothing to fear from dialogue, provided it was conducted as master and not as beggar. This is what makes him the true founder of the modern papacy, the one that speaks to the whole world over the heads of States.

The facts of this pontificate are established by first-rate sources: pontifical acts preserved on the Holy See website, standard Catholic reference notices and cross-checked biographical entries. The table below summarizes the main sources and what they contribute.

Before becoming the pope of dialogue with the century, Vincenzo Gioacchino Pecci was, for nearly forty years, a model administrator, diplomat and bishop. His very long episcopate in Perugia, far from central power, made him an experienced pastor more than a courtier — which partly explains the freedom of mind of his pontificate.

A family of minor nobility in Latium

Vincenzo Gioacchino Raffaele Luigi Pecci was born on 2 March 1810 in Carpineto Romano, a mountain town of Latium, in the Papal States.^[16][17] He was the sixth of seven children of Count Ludovico Pecci and Anna Prosperi-Buzi, a family of local minor nobility whose tradition traced its origins to the Pecci of Siena, settled in the States of the Church in the sixteenth century.^[18] Gioacchino's childhood unfolded in troubled times: the Italian peninsula was under Napoleonic domination, and Pius VII was the Emperor's prisoner. This context of a humiliated papacy would deeply mark his generation.

Formation with the Jesuits and at the Roman College

From 1818, the young Pecci was entrusted, with his brother Giuseppe, to the Jesuit college at Viterbo, where he showed early gifts for classical letters and Latin — a virtuosity later visible in the limpid prose of his encyclicals.^[19][20] He continued his studies at the Roman College of the Jesuits in Rome, then obtained a doctorate in theology (1832) and studied civil and canon law. Admitted to the Academy of Noble Ecclesiastics, the training ground of papal diplomats, he prepared for the service of the Holy See.^[21]

Apostolic delegate: Benevento and Perugia

Ordained priest on 31 December 1837, Pecci immediately entered the administration of the Papal States.^[22][23] Appointed apostolic delegate of Benevento (1838), a pontifical enclave in Neapolitan territory, the young prelate showed himself energetic: he broke the brigandage ravaging the province, reformed taxation and restored order.^[24] Transferred to Perugia as delegate (1841-1843), he developed the administration and founded a savings bank. These years as an administrator gave him concrete knowledge of social and economic realities that would illuminate Rerum Novarum half a century later.

Nuncio in Brussels (1843-1846)

In January 1843, Pecci was appointed apostolic nuncio in Brussels and consecrated titular archbishop of Damietta on 19 February 1843.^[25][26] Belgium, a young Catholic kingdom born in 1830, was then a laboratory of relations between the Church and a modern liberal State. The mission, amid sharp school disputes, was delicate, and the nuncio had to deal with the unionist ministry of J.-B. Nothomb, which united Catholics and liberals. There Pecci discovered from within the issues of a nascent industrial society and the difficulty of maintaining the rights of the Church within a constitutional framework.^[27] This Belgian experience was decisive: long before the fact, it made him a bishop sensitive to political and social modernity.

Thirty-two years as bishop of Perugia

Recalled in 1846, Pecci was appointed bishop of Perugia, a see he would occupy for thirty-two years (1846-1878).^[28][29] It was an exceptionally long and fruitful episcopate: he restored the seminary, encouraged the study of Saint Thomas Aquinas there, built or renovated dozens of churches, and deployed intense pastoral and charitable activity.^[30] Above all, in his pastoral letters of the 1870s, the bishop of Perugia already sketched the great themes of his future pontificate: the relations between the Church and civilization, the role of reason and faith, the place of labor and property. Far from Rome, away from the court of Pius IX, Pecci silently forged an original thought.

Cardinal and camerlengo: the long wait

Created cardinal-priest on 19 December 1853 by Pius IX, Pecci nevertheless long remained away from central power: according to several biographers, a falling-out with the all-powerful secretary of state, Cardinal Antonelli, may have contributed to his remaining in Perugia — but The Catholic Encyclopedia (1910) qualifies this account: Pecci himself preferred Perugia to the suburbicarian sees offered to him, and “it is certainly untrue that Pius IX designedly left him in Perugia.”^[31][32] Only in 1877, after Antonelli's death, did the situation change: Pius IX called Pecci to Rome and appointed him camerlengo of the Holy Roman Church — the office that administers the Church during the vacancy of the Apostolic See.^[33][34] At sixty-seven, the old cardinal of Perugia thus found himself, by an unforeseen reversal, at the center of the machinery precisely as the death of Pius IX approached.

The death of Pius IX and the shadow of the Roman Question

Pius IX died on 7 February 1878, after the longest pontificate in history (nearly thirty-two years). His death came in a tense climate: Rome had been annexed by the Kingdom of Italy in 1870, then established as its capital in 1871; the Papal States had disappeared, and the pope considered himself a prisoner in the Vatican.^[35] For the first time in centuries, a conclave was held in a Rome that had become Italian and no longer pontifical — some cardinals even feared that it would have to be moved outside Italy. In the end, the Italian government guaranteed the freedom of the conclave, which was held in the Vatican.^[36]

The election of 20 February 1878

Sixty-one cardinals took part in the conclave that opened on 18 February. Camerlengo Pecci appeared as the favorite of the moderates: they wanted a pope capable of continuing the work of Pius IX by other means, without renouncing her principles. On the third ballot, on 20 February 1878, Cardinal Pecci was elected by forty-four votes out of sixty-one — well beyond the required two-thirds majority.^[37][38] He took the name Leo XIII.

Doctrinally conservative but open in method, Pecci was quickly elected, on the third ballot, by cardinals who saw in him the man capable of restoring the papacy's prestige without cutting it off from its time.^[39]

He was thought frail: elderly, delicate in health, he was imagined as a brief transitional pope. Instead, his became one of the longest and most significant pontificates in history — twenty-five years and five months.^[40] Church history is rich in these “transitional popes” who lasted a quarter of a century.

The choice of the name Leo

By choosing the name Leo, Pecci placed himself in the line of great reforming and faith-defending Leos, up to Saint Leo the Great. The name announced a program: doctrinal authority, culture and firm government, but also radiance. Leo XIII intended to be a pope who teaches — and indeed, his magisterium through encyclicals was unprecedented in scale.

The first great doctrinal act of the reign concerns philosophy. On 4 August 1879, barely more than a year after his election, Leo XIII published the encyclical Aeterni Patris, which restored the study of Saint Thomas Aquinas as the foundation of Catholic thought.^[41] The pope starts from an observation: modern errors — rationalism, positivism, materialism — prosper because Catholic minds lack a solid philosophy with which to answer them. Reason must therefore be restored to its rights, but a reason enlightened by faith and structured by the great medieval synthesis.

“We exhort you, venerable brethren, in all earnestness to restore the golden wisdom of St. Thomas, and to spread it far and wide for the defense and beauty of the Catholic faith, for the good of society, and for the advantage of all the sciences.” — Leo XIII, Aeterni Patris, 4 August 1879 (official English translation published by the Holy See)^[42]

The encyclical asks that the doctrine of Thomas Aquinas be taught in seminaries and Catholic universities, and that it serve to refute the errors of the time. The effect was considerable: Aeterni Patris launched the great movement of neo-Thomism, founded institutions such as the Higher Institute of Philosophy in Louvain, and shaped the intellectual formation of generations of clerics until Vatican II. Leo XIII did not want an archaeological return to the Middle Ages, but a reason reconciled with faith, capable of dialoguing on equal terms with modern science. The detail of this philosophy belongs to the articles on Saint Thomas Aquinas and the Summa Theologiae; what belongs to Leo XIII is to have made it the official foundation of Catholic teaching.

The most famous and lasting act of the pontificate is the encyclical Rerum Novarum, published on 15 May 1891. It addresses head-on the social question — the condition of workers in a Europe transformed by the Industrial Revolution — and lays the modern foundations of what would be called the social doctrine of the Church: not an economic system invented in 1891, but the development, for modern times, of a moral teaching rooted in Catholic Tradition.^[43] For the first time, a pope devoted an entire magisterial document to the world of labor, and did so with such authority that all later social encyclicals would present themselves as its heirs.

The diagnosis: the condition of workers

Leo XIII begins from a clear-sighted observation: the spirit of revolutionary upheaval disturbing Europe has reached the economic field, and the concentration of wealth has delivered the mass of workers to undeserved misery.

“That the spirit of revolutionary change, which has long been disturbing the nations of the world, should have passed beyond the sphere of politics and made its influence felt in the cognate sphere of practical economics is not surprising.” — Leo XIII, Rerum Novarum, 15 May 1891, § 1 (official English translation published by the Holy See)^[44]

The pope describes exploitation without evasions: the disappearance of the old guilds, the absence of legal protection, usury, and isolated workers being handed over to “unchecked competition” and to the hardness of greedy employers. The tone is firm: this is not a vague appeal to charity, but a social analysis.

Against socialism: the defense of property

But Leo XIII rejects the false solution of socialism, which claims to solve misery by abolishing private property. The remedy, he says, would be worse than the evil: it would harm the workers themselves, violate justice and overturn social order. The pope therefore defends the natural right to property as a legitimate extension of work and foresight.

“Every man has by nature the right to possess property as his own.” — Leo XIII, Rerum Novarum, 15 May 1891, § 6 (official English translation published by the Holy See)^[45]

This is one of the decisive axes of the encyclical: against collectivism, the Church affirms that property is a right; but against absolute liberalism, she immediately recalls that this right carries duties, and that goods, legitimately possessed, must serve the common good. The detail of this refutation belongs to the article on socialism; Leo XIII lays down its principles here.

The just wage and the dignity of labor

The spiritual heart of the encyclical is the dignity of the worker, created in the image of God, whose labor cannot be treated as a mere commodity. From this flows the requirement of the just wage: not merely the price set by a “free” contract, but pay sufficient to allow a sober and honest worker and his family to live with dignity.

“To defraud any one of wages that are his due is a great crime which cries to the avenging anger of Heaven.” — Leo XIII, Rerum Novarum, 15 May 1891, § 20 (official English translation published by the Holy See)^[46]

This phrase, echoing a cry from Scripture, struck minds forcefully: it makes fair payment for labor an obligation of justice, not of mere employer benevolence. It is what earned Leo XIII the nickname “pope of workers” and made Rerum Novarum a text venerated far beyond Catholic borders.

The role of the State and of associations

Finally, the encyclical traces the duties of the State and the legitimacy of workers' associations. The State must protect the weak, limit working hours, defend Sunday rest and watch over the health of workers, without absorbing everything. Workers have the right to associate — a prefiguration of Christian trade unions — to defend their interests. The development of these consequences belongs to the articles on social doctrine and on trade unions; what belongs to the pontificate itself is to have opened this project that all later popes would continue.

Alongside his social and intellectual work, Leo XIII deployed a vast teaching on Christian political order: what place should the Church hold in the city, and how should the great principles of modern liberalism be judged? Three major encyclicals form this corpus.

Immortale Dei (1885): the Christian constitution of States

By the encyclical Immortale Dei (1 November 1885), Leo XIII expounds Catholic doctrine on relations between Church and State.^[47] He teaches that public authority comes from God, that the two powers — spiritual and temporal — are distinct but ordered to the same final end of man, and that the State has the duty to render public worship to the true God. The pope rejects both caesaropapism (the State enslaving the Church) and secularism (the State declaring itself indifferent to every religion). The text provides the theoretical basis of the Catholic position facing the secular States multiplying in Europe.

Libertas (1888): true and false liberty

Three years later, Libertas (20 June 1888) treats human liberty.^[48] Leo XIII distinguishes true liberty — the power to choose the good, rooted in truth and moral law — from the modern liberties taken as absolutes: freedom of worship, speech, press and teaching erected into unlimited rights. He does not condemn them in a bloc, but refuses to found them on indifference to truth. His thesis is subtle: liberty detached from truth destroys itself — to paraphrase the encyclical, liberty is not the right to do anything whatever: “abandoning itself to such excesses, in contempt of truth and justice, liberty becomes vitiated and openly degenerates into licence.” This encyclical is one of the most nuanced magisterial texts on liberalism.

Humanum Genus (1884): against Freemasonry

In Humanum Genus (20 April 1884), the pope renews the condemnation of Freemasonry, which he presents as the most active organization of the “kingdom of Satan” against Christian order.^[49] Taking up the condemnations of Clement XII and his successors, he denounces Masonic naturalism — the idea that reason and nature suffice, without revelation or Church — which he judges to dissolve faith, morality and society. The details of Masonic history belong to a dedicated article; what belongs to Leo XIII is to have given this condemnation its classic formulation for the contemporary age.

Leo XIII's political genius unfolded above all on the international stage. Deprived of territory and army, the pope made diplomacy and moral authority his only weapons — and wielded them with an art that restored the prestige of the Holy See throughout the world. His great secretary of state, Cardinal Rampolla — created cardinal on 14 March 1887, called to the secretariat of state in June 1887 — was the architect of this policy of reconciliation.^[50][51]

The end of the German Kulturkampf

The first success was the liquidation of the Kulturkampf, the “struggle for civilization” that Chancellor Bismarck had launched against the Catholic Church in the German Empire (May Laws of 1873). After the frontal resistance offered under Pius IX, Leo XIII undertook patient negotiations. Gradually, the anti-Catholic laws were repealed: as early as 1882, diplomatic relations with Prussia were restored, and by about 1887 a modus vivendi ended the conflict.^[52] Supreme recognition of this recovered authority: in 1885, Bismarck chose Leo XIII as arbitrator in a territorial dispute between Germany and Spain over the Caroline Islands — a “prisoner” pope asked to decide between two great powers.^[53]

The Ralliement: accepting the French Republic

The boldest — and most debated — policy concerned France. Since the fall of the Empire, the Third Republic, dominated by anticlerical currents, had carried out a policy of secularization (school laws, expulsion of congregations). A large part of French Catholics, monarchist at heart, rejected the regime. Leo XIII judged this posture suicidal: by identifying themselves with a dead monarchy, Catholics condemned themselves to impotence and handed the Republic over to its enemies. Through the encyclical Au milieu des sollicitudes (16 February 1892) — exceptionally first published in French — he asked them to accept the established regime in order better to defend just laws and religion within it.^[54]

“Consequently, when new governments representing this unchangeable power are constituted, to accept them is not only permitted, but required, indeed even imposed by the necessity of the social good which created and maintains them.” — Leo XIII, Au milieu des sollicitudes, 16 February 1892 (original French text)^[55]

The distinction he establishes is famous: one must separate the regime (the form of power, here the Republic, perfectly acceptable) from the legislation (which can, under the best regime, be detestable and may lawfully be fought).^[56] This is the doctrine of the Ralliement. It met strong resistance and did not bear all the hoped-for fruits — French anticlericalism would culminate in the Separation of 1905, under Pius X — but it laid down a lasting principle: the Church identifies herself with no particular political form.

The Roman Question: the “prisoner of the Vatican”

On one point, however, Leo XIII remained uncompromising: the Roman Question, that is, the spoliation of the Papal States by the Kingdom of Italy in 1870. Like Pius IX, he refused to recognize the legitimacy of this conquest, considered himself a prisoner in the Vatican, and maintained the non expedit forbidding Italian Catholics to take part in the political life of the kingdom.^[57] This protest, which could seem to contradict his French flexibility, followed a logic: it was a matter of preserving the pope's spiritual independence, since he could not be the subject of any State. The Roman Question would not be resolved until 1929, long after his death, by the Lateran Agreements.

The English-speaking world: Newman, the United States, Americanism

Leo XIII paid particular attention to the Anglo-Saxon world, where Catholicism was then expanding strongly. In 1879, at the beginning of his reign, he created the illustrious English convert John Henry Newman a cardinal — a gesture rehabilitating a theologian long suspected.^[58] He restored the Catholic hierarchy in Scotland (1878) and in the Indies (1886), confirmed the decrees of the Plenary Council of Baltimore, created Archbishop Gibbons cardinal (1886), and erected an apostolic delegation in Washington (24 January 1893).^[59]

But he also intervened to correct certain tendencies. In 1899, through the letter Testem Benevolentiae, he warned against “Americanism”: the temptation to adapt Catholic doctrine to the spirit of the age, to minimize the so-called “passive” virtues — humility, obedience, patience — in favor of the “active” virtues of initiative and outward action, or to loosen the authority of the Church in order to seduce the modern world.^[60] The pope who advocated openness also knew how to mark its limits: dialogue with the century, yes; dilution of the faith in the air of the time, never.

Apostolicae Curae (1896): the nullity of Anglican ordinations

In the same spirit, Leo XIII settled a delicate ecumenical question. After multiplying gestures toward England — including the apostolic letter Amantissimae voluntatis to the English people, of 14 April 1895 —, he had the validity of Anglican ordinations examined. The conclusion, rendered by the apostolic letter Apostolicae Curae of 13 September 1896, is clear: Anglican orders, derived from the reformed sixteenth-century Ordinal — the official liturgical book of ordinations of the Church of England, revised at the Reformation —, are declared “absolutely null and utterly void.”^[61] The reason is not a moral accusation, but the analysis of the rite itself, judged deprived of the form and intention expressing the Catholic sacrificial priesthood. The text remains today the official reference for the Church's position on this point — its clarity shows that Leonine openness was never relativism.

Faithful to his conviction that faith does not fear truth, Leo XIII encouraged the sciences and scholarship, convinced that no authentic discovery can contradict Revelation.

Providentissimus Deus (1893): inerrancy and the study of Scripture

The encyclical Providentissimus Deus (18 November 1893) is the great charter of modern biblical studies.^[62] Against rationalist “higher criticism,” which disputed the historicity and inspiration of Scripture, Leo XIII strongly reaffirmed the inerrancy of the Bible: God is its author, and he cannot be the author of any error. Taking up the doctrine of Vatican I, he lays down as a principle that “it is absolutely forbidden to restrict inspiration to certain parts only of Sacred Scripture, or to concede that the sacred author himself could have erred” (DS 3291).^[63]

“It follows that those who maintain that an error is possible in any genuine passage of the sacred writings either pervert the Catholic notion of inspiration, or make God the author of such error.” — Leo XIII, Providentissimus Deus, 18 November 1893 (official English translation published by the Holy See)^[64]

Yet, far from closing the door to research, the pope encouraged Catholic exegetes to study ancient languages, textual criticism and profane sciences, in order to answer objections on the very ground of scholarship. This balance — firmness on inspiration, openness on method — gave a magisterial framework to biblical studies already under way: the École biblique de Jérusalem, founded as early as 1890 by Fr. Lagrange and supported by the pope, belongs within it, and the Pontifical Biblical Commission would be erected in 1902 to watch over the application of the encyclical. The detail of this doctrine belongs to the article on biblical inerrancy and scriptural studies; what belongs to the pontificate is to have given it its magisterial framework.

The opening of the Vatican Archives

A striking gesture of confidence in truth: in 1881, Leo XIII decided to open the Vatican Secret Archives to scholars, including non-Catholics and Protestants — a reading room was fitted out and the first historians admitted; the opening was solemnly confirmed in August 1883 by his letter Saepenumero considerantes to the cardinals in charge of the archives, which declared access open to all impartial research.^[65][66] The pope affirmed there his conviction that historical truth, far from harming the Church, serves her: the Church has nothing to fear from true history. This confidence in free research is one of the most modern marks of his reign, and it transformed Rome into one of the great centers of historical scholarship in the world.

Behind the diplomat and the doctor stood a man of deep piety, whose Marian, Christic and pneumatological devotion — that is, turned toward the Holy Spirit — permeated the whole magisterium. Far from being a mere administrator, Leo XIII was a praying pastor.

The pope of the Rosary

No pope promoted the Rosary as much as Leo XIII: he devoted eleven encyclicals to it — from Supremi apostolatus officio (1883) to Diuturni temporis (1898), according to the usual count which excludes Quod auctoritate (1885), of disputed corpus —, made October the month of the Rosary, and saw in it the spiritual weapon of difficult times.^[67] For him, the Rosary was not a minor devotion but a school of contemplation of the mysteries of Christ and a rampart against the errors of the century. This Marian zeal earned him the second of his nicknames: the “pope of the Rosary.”

The consecration of the human race to the Sacred Heart (Annum Sacrum, 1899)

One of the major spiritual acts of the pontificate was the consecration of the whole human race to the Sacred Heart of Jesus: prescribed by the encyclical Annum Sacrum of 25 May 1899, it was carried out on 11 June 1899, on the feast of the Sacred Heart, in the churches of the whole world.^[68] Taking up the promises made to Saint Margaret Mary Alacoque, the pope proclaimed the social kingship of Christ over peoples and nations, and placed all humanity under the protection of his Heart.

“When the Church, in the days immediately succeeding her institution, was oppressed beneath the yoke of the Caesars, a young Emperor saw in the heavens a cross, which became at once the happy omen and cause of the glorious victory that soon followed. And now, to-day, behold another blessed and heavenly token is offered to our sight — the most Sacred Heart of Jesus, with a cross rising from it and shining forth with dazzling splendor amidst flames of love.” — Leo XIII, Annum Sacrum, 25 May 1899, § 12 (official English text published by the Holy See; there is no official French edition of this text on vatican.va)^[69]

This act, which crowned the whole nineteenth-century movement of devotion to the Sacred Heart, reveals the spiritual foundation of the reign: beyond diplomacy and doctrine, Leo XIII wanted to submit all society to the reign of Christ's love.

Devotion to Saint Joseph and to the Holy Spirit

The pope also developed devotion to Saint Joseph — proclaimed patron of the universal Church by Pius IX (decree Quemadmodum Deus, 8 December 1870), whom Leo XIII in turn proposed as a model of workers and whose cult he prescribed (encyclical Quamquam Pluries, 1889)^[70] —, and to the Holy Spirit, to whom he devoted the encyclical Divinum Illud Munus (1897)^[71], inviting the faithful to a renewed devotion toward the third Person of the Trinity. These devotions are not incidental: they reveal a coherent spiritual theology, in which work, family and sanctification find their source in God.

An exceptional longevity (1903)

Leo XIII's reign was as long as his life was exceptionally long. The pope died in Rome on 20 July 1903, aged ninety-three — one of the oldest popes in history — after more than twenty-five years of pontificate, one of the longest ever verified.^[72] To the end, despite fragile health preserved by the methodical regularity of his life, he had worked tirelessly, dictating encyclicals and letters with intact lucidity.^[73] First buried at Saint Peter's, his body was transferred in 1924 to the basilica of Saint John Lateran, his cathedral as bishop of Rome, where his monumental tomb rests.

The verdict of history

On the doctrinal level, Leo XIII refounded Catholic philosophy (Aeterni Patris), gave social doctrine its modern development (Rerum Novarum), framed modern exegesis (Providentissimus Deus) and clarified the Church's political doctrine. On the diplomatic level, he drew the papacy out of isolation, ended the Kulturkampf, attempted the Ralliement and restored to the Holy See a moral authority heeded by the powers. On the spiritual level, he consecrated humanity to the Sacred Heart and spread the Rosary. Such is the documented record of the reign.

“On the whole, his pontificate of twenty-five years was certainly, in external success, one of the most brilliant.” — The Catholic Encyclopedia (1910), article “Pope Leo XIII” (translation)^[74]

The same notice stresses his tireless labor and the outpouring of popular sympathy shown at his three jubilees: it is on these facts — and not on legend — that his reputation as a great diplomat and doctor-pope rests.

Not everything succeeded: the Ralliement partly failed, the Roman Question remained open, and French anticlericalism temporarily triumphed. But Leo XIII had shown a path: that of a Church faithful to truth and open to the world, which does not fight modernity by withdrawing, but by evangelizing it from within. His immediate successor, Cardinal Sarto, took the name Pius X and would steer the course toward greater firmness; but it is in Leo XIII's wake that twentieth-century social doctrine, the Thomistic renewal and the prudent ecumenism that would culminate at Vatican II would develop. The pope of Carpineto thus remains, in the long gallery of the successors of Peter, the figure of dialogue without capitulation.

• Blessed Pius IX — his predecessor, the pope of the Syllabus, of the Immaculate Conception and of the loss of the Papal States.
• Pope Saint Pius X — his immediate successor, who redirected the policy of the Ralliement and faced the Separation of 1905.
• Pope Leo XII — one of the predecessors whose name and zeal Vincenzo Pecci admired.
• Rerum Novarum and the social doctrine of the Church — the dedicated article on the great social encyclical of 1891.
• Saint Thomas Aquinas and the Summa Theologiae — the thought Leo XIII restored through Aeterni Patris in 1879.
• Saint John Henry Newman — the great English convert whom Leo XIII created cardinal in 1879.
• Socialism and its limits and Trade unions and social doctrine — the questions opened by Rerum Novarum.