chief channels are the various systems
of heathen philosophy, and more especially the thoughts of Plato and the
methods of Aristotle. Reason and revelation are separate sources of
knowledge; and man can put himself in possession of each, because he can
bring himself into relation to the church on the one hand, and the
system of philosophy, or more strictly Aristotle, on the other. The
conception will be made clearer when it is remembered that Aquinas,
taught by the mysterious author of the writings of the pseudo-Dionysius,
who so marvellously influenced medieval writers, sometimes spoke of a
natural revelation, or of reason as a source of truths in themselves
mysterious, and was always accustomed to say that reason as well as
revelation contained two kinds of knowledge. The first kind lay quite
beyond the power of man to receive it, the second was within man's
reach. In reason, as in revelation, man can only attain to the lower
kind of knowledge; there is a higher kind which we may not hope to
reach.

But while reason and revelation are two distinct sources of truths, the
truths are not contradictory; for in the last resort they rest on _one_
absolute truth--they come from the one source of knowledge, God, the
Absolute One. Hence arises the compatibility of philosophy and theology
which was the fundamental axiom of scholasticism, and the possibility of
a Summa Theologiae, which is a Summa Philosophiae as well. All the many
writings of Thomas are preparatory to his great work the _Summa
Theologiae_, and show us the progress of his mind training for this his
life work. In the _Summa Catholicae Fidei contra Gentiles_ he shows how
a Christian theology is the sum and crown of all science. This work is
in its design apologetic, and is meant to bring within the range of
Christian thought all that is of value in Mahommedan science. He
carefully establishes the necessity of revelation as a source of
knowledge, not merely because it aids us in comprehending in a somewhat
better way the truths already furnished by reason, as some of the
Arabian philosophers and Maimonides had acknowledged, but because it is
the absolute source of our knowledge of the mysteries of the Christian
faith; and then he lays down the relations to be observed between reason
and revelation, between philosophy and theology. This work, _Contra
Gentiles_, may be taken as an elaborate exposition of the method of
Aquinas. That method, however, implied a careful