«AETERNI PATRIS». – Opening words of the encyclical with which Leo XIII, on 4 Aug. 1879, recalled Thomistic philosophy to honour.
Noting how false doctrines open the way to bad conduct both individual and social, the encyclical observes that sound philosophy disposes the mind to faith, shows the reasonableness of adherence to revelation, makes its content better understood, defends its gains, while from faith it receives light and protection. The Fathers of the Church made use of what was healthy in pagan philosophy and enlarged it with Christian wisdom. The scholastics in turn demonstrated more clearly the harmony between reason and faith through refined logical procedure and sober eloquence. Among them, St Thomas stands out for his exceptional gifts of an angelic mind, reducing the currents of scholastic thought to unity by eliminating and integrating.
The Church, which has always acknowledged this primacy of the Angelic Doctor, points out the harm done to learning and society by the neglect shown by moderns toward that philosophy. The Pope intends to restore it to honour for the solid formation of the clergy, for effective apostolate among those learned men who claim to follow reason alone, for the security of the social order, and for the progress of all the sciences and arts that draw light and direction from philosophy. Nothing merely ephemeral from the scholastics is to be accepted, yet what is gold must be enriched by every subsequent gain.
To ensure that the great reform did not remain on paper, Leo XIII, in the same year 1879, addressed an apostolic letter to Cardinal De Luca for the foundation in Rome of a Thomistic academy ordered to the study and defence of the restored philosophy. On 4 Aug. 1880 he declared St Thomas patron of all Catholic schools, and by a motu proprio of the same year ordered a critical edition of all the works of St Thomas, assigning thereto a fund of 300,000 lire. In 1889 he wrote to Cardinal Goossens, archbishop of Malines, congratulating him on the foundation of an advanced institute of Thomistic philosophy at the University of Louvain, praising and confirming the choice of D. Mercier as its head and promising to contribute to its expenses. Thus the great Pontiff extended to the universal Church what he had already done for his own diocese as bishop of Perugia, where, to form a learned clergy, he had founded a Thomistic academy dating back to 1872—hence even before that of Naples, which dates from 1874—and among its members were numbered Luigi and Anastasio Rotelli, Gabriele Boccali, Geremia Brunelli, Giuseppe Cernicchi, Giuseppe Pecci (brother of Gioacchino), Federico Foscati, Fabio Ferrini and Monsignor F. Satolli.
Whoever knows the state of philosophy, even in Catholic schools, before A.P., understands the words of Pius XI in his letter to Cardinal Bisleti of 10 Aug. 1922 (AAS, [vol. 14] pp. 449-58): «If Leo XIII had no other merits toward the Church than this of having restored Thomistic philosophy, it would alone suffice to immortalise his memory.» Cardinal Mercier was thus able to sum up the effects of that reform: «The encyclical A.P. has indeed restored to honour the philosophy of the great masters of scholasticism, restored unity of teaching to the Catholic Church, and drawn the attention of learned men outside the faith to a host of ideas hitherto unknown to them» (op. cit. in the bibliography, p. 328).