study and comprehension
of the results which accrued to man from reason and revelation, and a
thorough grasp of all that had been done by man in relation to those two
sources of human knowledge; and so, in his preliminary writings, Thomas
proceeds to master the two provinces. The results of revelation he found
in the Holy Scriptures and in the writings of the fathers and the great
theologians of the church; and his method was to proceed backwards. He
began with Peter of Lombardy (who had reduced to theological order, in
his famous book on the _Sentences_, the various authoritative statements
of the church upon doctrine) in his _In Quatuor Sententiarum P. Lombardi
libros_. Then came his deliverances upon undecided points in theology,
in his _XII. Quodlibeta Disputata_, and his _Quaestiones Disputatae_.
His _Catena Aurea_ next appeared, which, under the form of a commentary
on the Gospels, was really an exhaustive summary of the theological
teaching of the greatest of the church fathers. This side of his
preparation was finished by a close study of Scripture, the results of
which are contained in his commentaries, _In omnes Epistolas Dim
Apostoli Expositio_, his _Super Isaiam et Jeremiam_, and his _In
Psalmos_. Turning now to the other side, we have evidence, not only from
tradition but from his writings, that he was acquainted with Plato and
the mystical Platonists; but he had the sagacity to perceive that
Aristotle was _the_ great representative of philosophy, and that his
writings contained the best results and method which the natural reason
had as yet attained to. Accordingly Aquinas prepared himself on this
side by commentaries on Aristotle's _De Interpretatione_, on his
_Posterior Analytics_, on the _Metaphysics_, the _Physics_, the _De
Anima_, and on Aristotle's other psychological and physical writings,
each commentary having for its aim to lay hold of the material and grasp
the method contained and employed in each treatise. Fortified by this
exhaustive preparation, Aquinas began his _Summa Theologiae_, which he
intended to be the sum of all known learning, arranged according to the
best method, and subordinate to the dictates of the church. Practically
it came to be the theological dicta of the church, explained according
to the philosophy of Aristotle and his Arabian commentators. The _Summa_
is divided into three great parts, which shortly may be said to treat of
God, Man and the God-Man. The first and the seco