God to be worshipped, any book on Moral Science is incomplete without
a chapter on Religion. But the question remains, whether the name of
God should enter into the other chapters, and His being and authority
into the very foundations of the science. I do not mean the
metaphysical foundations; for Metaphysics are like a two-edged sword,
that cleaves down to the very marrow of things, and must therefore
reveal and discover God. But Morality, like Mathematics, takes certain
metaphysical foundations for granted, without enquiring into them. On
these foundations we rear the walls, so to speak, of the science of
Ethics without reference to God, but we cannot put the roof and crown
upon the erection, unless we speak of Him and of His law. Moral
distinctions, as we saw (c. vi., s. i. n. 7, p. 113), are antecedent
to the Divine command to observe them: and though they rest ultimately
on the Divine nature, that ultimate ground belongs to Metaphysics, not
to Ethics. Ethics begins with human nature, pointing out that there
are certain human acts that do become a man, and others that do not.
(c. vi., s. i., p. 109.) To see this, it is not necessary to look up
above man. Thus we shall prove lying, suicide, and murder to be wrong,
and good fellowship a duty, without needing to mention the Divine
Being, though by considering Him the proof gains in cogency. Or
rather, apart from God we shall prove certain acts wrong, and other
acts obligatory as duties, _philosophically_ speaking, with an initial
and fundamental wrongness and obligation. In the present section we
have proved once for all, that what is wrong philosophically, or is
philosophically a duty, is the same also _theologically_. Thus the
initial and fundamental obligation is transformed into an obligation
formal and complete. Therefore, hereafter we shall be content to have
established the philosophical obligation, knowing that the theological
side is invariably conjoined therewith. As St. Thomas says (1a 2a, q.
71, art. 6, ad 5): "By theologians sin is considered principally as it