The fact that Robert Cardinal Prevost has taken the name Leo IV, indicating his respect for his predecessor, Leo XIII, provides Catholics with a strong incentive to return to the latter’s encyclicals. Pope Leo’s encyclical Rerum Novarum which the new pope mentioned in particular, deals with the worker. The encyclical outlined here, Aeterni Patris, concerns philosophy. There can be no doubt that these two encyclicals complement each other while providing important contributions concerning how Catholics should live and how they should think.
Like Rerum Novarum, (“On the Condition of Labor”), Aeterni Patris (“Of the Eternal Father”) is of particular relevance for today’s world that suffers from both social injustice and intellectual confusion. The sesquipedalian title given to Aeterni Patris is “On the Restoration of Christian Philosophy in the Spirit of the Angelic Doctor, St. Thomas Aquinas.”
The expression “Christian Philosophy” may seem contradictory to some, but Leo XIII explains how they support each other, being mutually beneficial:
For, not in vain did God set the light of reason in the human mind; and so far is the superadded light of faith from extinguishing or lessening the power of the intelligence that it completes it rather, and by adding to its strength renders it capable of greater things.
The philosophy of St. Thomas Aquinas is developed independently of faith. Its principles depend solely on reason and experience. Although it is completely distinct from faith, the Angelic Doctor’s philosophy is in vital communication with the superior wisdoms of theology. The harmony between reason and faith was one of the great contributions that Aquinas made to a world in which faith and reason were thought to be independent of each other. This problem persists in today’s world where faith and reason appear to be strangers to each other. Nonetheless, as Pope Leo XIII writes, “Faith frees and saves reason from error, and endows it with manifold knowledge.”
Leo states that, “false conclusions concerning divine and human things, which originated in the schools of philosophy, have now crept into all the orders of the State, and have been accepted by the common consent of the masses.” These words have direct pertinence to today’s situation. We cite deconstruction, relativism, nihilism, and situation ethics as a few examples of aberrant modes of thinking that flow from schools of higher education. Leo points out the fundamental importance of using reason as a guide through life, stating:
. . . if the intellect sins at all his will soon follows; and thus it happens that false opinions, whose seat is in the understanding, influence human actions and pervert them. Whereas, on the other hand, if men be of sound mind and take their stand on true and solid principles for the public, there will result a vast amount of benefit for the public and private good.
Why does Pope Leo assign pre-eminent importance to the thinking of St. Thomas Aquinas? His answer, at least in part, is as follows:
Among the scholastic Doctors, the chief and master of all, towers Thomas Aquinas, who, as Cajetan observes, because “he most venerated the ancient doctors of the Church, in a certain way seems to have inherited the intellect of all.”
Leo recognized that society was operating according to a false understand of liberty, a notion of liberty that was “running into license.” Here, once again, we find a strong correlation between the social problems of 1879 and those of 2025.
The conclusions of Aeterni Patris were implemented one year later by an apostolic letter written by Leo XIII establishing Thomas Aquinas as the common patron of all Catholic schools. As a result, a remarkable revival of Thomism took place. Because of the amplitude of its principles, Thomism was regarded as being applicable in all times.
In his first of eighty-eight encyclicals, Inscrutabili Dei Consilio (“On the Evils of Society”), 1878, Leo XIII recalled the words of St. Paul: “Beware lest any man cheat you by philosophy and vain deceit, according to the tradition of man, according to the principles of the world, and not according to Christ” (Col. 2:8). Leo argues that the safest way to keep false philosophies out of schools is to teach the true one, epitomized by the philosophy of St. Thomas Aquinas.
When the case was heard for the canonization of Aquinas, Bartolommeo di Capua made the following testimony:
Friar Giacomo di Viterbo, Archbishop of Naples, often said to me that he believed in accordance with the Faith and the Holy Spirit, that our Savior had sent, as doctor of truth to illuminate the world and the universal Church, first the apostle Paul, then Augustine, and finally in these latest days, Friar Thomas, whom, he believed, no one would succeed till the end of the world.
Toward the end of Aeterni Patris, Leo directs his message to “All Our Venerable Brethren, the Patriarchs, Primates, Archbishops and Bishops,” with passion and conviction:
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 good of society, and for the advantage of all the sciences. . . . Let carefully selected teachers endeavor to implant the doctrine of Thomas Aquinas in the minds of students, and set forth clearly his solidity and excellence over others.
History has shown how well the words of Pope Leo XIII were put to good use. May the restoration of Rerum Novarum, under the tutelage of Pope Leo XIV, have similar results.
Image from Wikimedia Commons
