Scholasticism inaugurated a new era. Patristic erudition had gathered a wealth of theological knowledge which the Schoolmen fully appreciated. But the same truths were to receive another setting and be treated by different methods. Speculation changed its direction, Aristotle taking the place of his master. The peripatetic system found able exponents in the earlier Scholastics; but Aquinas surpassed them alike in the mastery of the philosopher's principles and in his application of these principles to Christian doctrine. His Commentaries on Aristotle adhere strictly to the text, dissecting its meaning and throwing into relief the orderly sequence of ideas. In his other works, he develops the germs of thought which he had gathered from the Stagirite, and makes them the groundwork of his philosophical and theological speculations.
With the subtlety of a metaphysician St. Thomas combined a vast erudition. Quotations from the Fathers appear on nearly every page of his writings, serving either as a keynote to the discussion which follows, or as an occasion for solving objections. Toward St. Augustine he shows the deepest reverence, though their methods differ so widely, and his brief but lucid comments throw light on difficult sayings of the great Doctor. His familiarity with patristic theology is shown particularly in the 'Catena Aurea,' where he links with passages from the Sacred Text numerous extracts from the older commentators.
His respect for these interpretations did not prevent him from making a thorough search of Scripture itself. With characteristic clearness and depth he interpreted various books of the Bible, insisting chiefly on the doctrinal meaning. The best of his work in this line was devoted to the Pauline Epistles and to the Book of Job; but his mastery of each text is no less evident where he takes the authority of Scripture as the starting-point in theological argument, or makes it the crowning evidence at the close of a philosophical demonstration.
The materials gathered from Philosophy, Tradition, and Scripture were the fruit of analysis; the final synthesis had yet to be accomplished. This was the scope of the 'Summa Theologica,' a work which, though it was not completed, is the greatest production of Thomas Aquinas. In the prologue he says:--
"Since the teacher of Catholic truth should instruct not only those who are advanced, but also those who are beginning, it is our purpose in this work to treat subjects pertaining to the Christian religion in a manner adapted to the instruction of beginners. For we have considered that young students encounter various obstacles in the writings of different authors: partly because of the multiplication of useless questions, articles, and arguments; partly because the essentials of knowledge are dealt with, not in scientific order, but according as the explanation of books required or an occasion for disputing offered; partly because the frequent repetition of the same things begets weariness and confusion in the hearer's mind. Endeavoring, therefore, to avoid these defects and others of a like nature, we shall try, with confidence in the Divine assistance, to treat of sacred science briefly and clearly, so far as the subject-matter will allow."
The work intended for novices in theology, and so unpretentiously opened, is then portioned out in these words:--
"Whereas, the chief aim of this science is to impart a knowledge of God, not only as existing in Himself, but also as the origin and end of all things, and especially of rational creatures, we therefore shall treat first of God; second, of the rational creature's tendency toward God; third, of Christ, who as man is the way whereby we approach unto God. Concerning God, we shall consider (1) those things which pertain to the Divine Essence; (2) those which regard the distinction of persons; (3) those which concern the origin of creatures from Him. As to the Divine Essence we shall inquire (1) whether God exists; (2) what is, or rather what is not, the manner of His existence; (3) how He acts through His knowledge, will, and power. Under the first¸ heading we shall ask whether God's existence is self-evident, whether it can be demonstrated, and whether God does exist."
Similar subdivisions precede each question as it comes up for discussion, so that the student is enabled to take a comprehensive view, and perceive the bearing of one problem on another as well as its place in the wide domain of theology. As a consequence, those who are familiar with the 'Summa' find in it an object-lesson of breadth, proportion, and orderly thinking. Its chief merit, however, lies in the fact that it is the most complete and systematic exhibition of the harmony between reason and faith. In it, more than in any other of his works, is displayed the mind of its author. It determines his place in the history of thought, and closes what may be called the second period in the development of Christian theology. Scholasticism, the high point of intellectual activity in the Church, reached its culmination in Thomas Aquinas.
His works have been a rich source of information for Catholic theologians, and his opinions have always commanded respect. The polemics of the sixteenth century brought about a change in theological methods, the positive and critical elements becoming more prominent. Modern rationalism, however, has intensified the discussion of those fundamental problems which St. Thomas handled so thoroughly. As his writings furnish both a forcible statement of the Catholic position and satisfactory replies to many current objections, the Thomistic system has recently been restored. The "neo-scholastic movement" was initiated by Leo XIII. in his Encyclical 'Æterni Patris,' dated August 4th, 1879, and its rapid growth has made Aquinas the model of Catholic thought in the nineteenth century, as he certainly was in the thirteenth.
The subjoined extracts show his views on some questions of actual importance, with regard not alone to mediæval controversies, but to the problems of the universe, which will press on the minds of men twenty-five hundred years in the future as they did twenty-five hundred years in the past.