Franz Brentano has been traveling to Münster since 1859 to hear the lessons of Franz Jakob Clemens, considered the initiator of German neo-scholasticism; then he decides to achieve his doctorate in philosophy with a work on Suarez; moreover, in the same city, where he remained until March 1861, he maintained fruitful and frequent personal and scientific relationships with Christoph Bernhard Schlüter, master of the neo-scholastic historian C. Baeumker and precursor of Hermann Ernst Plassmann and Joseph Kleutgen.
In the span of time that covers the years of his formation and at least those of his teaching in Würzburg (1866-1873), Brentano aims at a project for the renewal of Thomism, through a “new understanding of Aristotle”. The main documents that allow us to identify and clearly recognize this program consist mainly of some letters that he exchanges, between June 2, 1861 and February 16, 1863, with Christoph Bernhard Schlüter and also by the correspondence between the poet Luise Hensel – faithful friend of Clemens Brentano and Franz’s aunt, that is Frau von Savigny born Gundel Brentano – and Schlüter himself and his sister Therese. From these epistolary exchanges it turns out that the young man goes to Münster in the summer semester of 1859 to be “introduced more deeply into the thought of Thomas Aquinas” by Clemens and addresses, through his mother Emilie Brentano born Genger who to his time he recommends it to the poet Luise Hensel, to Schlüter for help in this sense. Brentano will have frequent and regular personal contacts with the latter throughout the period of his stay in the city of Westphalia, where he will remain not a single semester, as was in his initial project, but at least until March 15, 1861, despite his master Clemens in the meantime he falls seriously ill and goes to the south of France to rest and heal himself. Schlüter, for his part, fully understands the value and will always remember with great sympathy and esteem of Franz Brentano and the pleasant, long and fruitful, hours spent with him talking especially about Baader and Suarez. On May 23, 1859, writing to his sister Therese, married Junkmann, he will speak of him as a polite young man, with a lovable character, of undoubted intelligence and great ability, versed in all disciplines of the spirit and sciences, who captures the core of the discussions without the need for many turns of words and with which it is very pleasant to be together and discuss. Three months later, that is, on August 23 of the same year, he will talk about regular meetings with him, followed by readings of philosophical texts and discussions. Finally, on April 17, 1863, in a letter addressed to Luise Hensel, he said that he had received the book by Franz Brentano on the multiple meanings of being in Aristotle and that he had found an exemplary job.
Franz Brentano himself is no less in praising Schlüter and, in particular, Clemens. So much so that, from Münster on May 31, 1859, addressing his aunt Kunigunda von Savigny, born Brentano, he wrote about his plans and the underlying reasons for his stay in the local university and haparole highly praised towards Clemens.
Clemens in this letter finds a significantly privileged image and is indicated in no uncertain terms by Brentano as the philosopher who, more than any other, transmits to him “deep respect and trust” and is therefore in all respects the “professor of my desires ». And Clemens, in his interpretation of Aristotle, made explicit above all in an essay – appeared anonymous, but certainly attributable to him -, in “Katholik” of 1858 and as a basic writing that inaugurated the new series of the magazine, of which he was the philosopher more representative, entitled Unser Standpunkt in der Philosophie, he had already indicated the programmatic lines of a resumption of Scholasticism, provoking a wide debate in the context of German Catholicism.
This scientific activity of Franz Brentano was part of the cultural and religious climate that had one of its driving forces in the Episcopal seminary of Mainz – around Bishop Ketteler -, and intended to oppose, with the return to the thought of Scholasticism, the idealistic philosophy seen as an expression both of liberal Protestantism and of the German nationalist movement. The young philosopher moved in line here, also mediated by Trendelenburg, who since the late 1950s characterized his studies, that is, the joint interest in Aristotle and his unsurpassed commentator St. Thomas. He had followed, in fact, in 1858 and for a semester the lessons in Berlin of the Stagirita scholar and then he had increasingly approached, on his impulse, the comments of Aquinas “in which Aristotle finds himself exposed more accurately than many commentators rear. ” The same solicitations had received them from his own family context, in particular from his father Christian, linked by relationships of close collaboration to the circle of Mainz, to Bishop Ketteler as well as to Christoph Moufang and Johann Baptist Heinrich (1816-1891), who had assumed the editing of the magazine “Katholik” – which became, precisely because of their direction, expression and organ of the German neo-scholastic movement -, soon entered a collision course in particular with the Tübingen School and with the magazine “Tübinger Theologischer Quartalschrift” which was inspired to German Idealism. “Katholik”, then, in general, opposed modern philosophy in that it aims to perpetuate the legacy of the Protestant Reformation, “root of every error”, of every form of subjectivism and confusion and, therefore, in need of being remedied through the use of the hermeneutic key provided by the Scholastica which also allows an adequate and correct understanding of ancient philosophy.
In this cultural milieu, Aristotelianism and Thomism not only end up being inseparable, but Aquinas is seen as the author who brought to fruition the most mature fruit of Greek philosophy, integrating it within Christian truth, in one historical development that led to the elaboration and articulation of philosophia perennis, that is, to a concept in which philosophy, science and theology are no longer understood as historically conditioned, but by Clemens and by the management of the magazine “Katholik” characterized in terms of a real system. To use Clemens’ words, in harmony with the positions expressed in Italy by the “Catholic Civilization” in the same years, Neo-Scholasticism is to be considered as that philosophy heir of ancient wisdom, which passed through the filter of the mediation and systematization activity of the Greeks, it was then “completed and developed in accordance with the revelation”, and at the same time illuminated and made fruitful, to the point that it took on “an almost mathematical, rigorously scientific form until it became the universal doctrine of the Catholic Schools [. ..] which brought together the wisdom of the new Christian world with the ancient one and carried on the scientific tradition “). However, adherence to Neo-Scholasticism, this adhesion is not to be understood in an uncritical way, as if it were a question of following in all and for all Saint Thomas, «in all its doctrines and exclusively […] without taking into consideration the Fathers and other representatives of Scholasticism “, without as if in his thought there was” nothing to change, improve or integrate, and it was enough to solve all the problems of the present and we no longer had anything else to do than propose it again, make it accepted and introduce it in the Schools ».