should be grades in
men as in other things. We see this in the elements, a superior and
an inferior; we see in every mixture that some one element
predominates.... For we see this also in the relation of the body and
the mind, and in the powers of the mind compared with one another;
because some are ordained towards ordering and moving, such as the
understanding and the will; others to serving. So should it be among
men; and thus it is proved that some are slaves according to nature.
Some lack reason through some defect of nature; and such ought to be
subjected to servile works because they cannot use their reason, and
this is called the natural law.'[4] In the same chapter the right of
conquerors to enslave their conquered is referred to without comment,
and therefore implicitly approved by the author.

[Footnote 1: II. ii. 57, 3.]

[Footnote 2: _Supra_, p. 64.]

[Footnote 3: II. ii 57, ad. 2.]

[Footnote 4: _De Reg. Prin._, ii. 10.]

'Thus,' according to Janet, 'St. Thomas admits slavery as far as one
can admit it, and for all the reasons for which one can admit it.
He admits with Aristotle that there is a natural slavery; with St.
Augustine that slavery is the result of sin; with the jurisconsult
that slavery is the result of war and convention.'[1] 'The author
justifies slavery,' says Franck, 'in the name of St. Augustine, and in
that of Aristotle; in the name of the latter by showing that there are
two races of men, one born to command, and the other to obey; in
the name of the former in affirming that slavery had its origin in
original sin; that by sin man has forfeited his right to liberty.
Further, we must admit slavery as an institution not only of nature
and one of the consequences of the fall, we must admit a third
principle of slavery which appears to St. Thomas as legitimate as the
other two. War is necessary; therefore it is just; and if it is just
we must accept its consequences. One of these consequences is the
absolute right of the conqueror over the life, person, and goods of
the conquered.'[2]

[Footnote 1: _Op. cit._, vol. i. p. 431.]

[Footnote 2: Franck, _op cit_., p. 69.]

Aquinas returns to the question of slavery in another passage, which
is interesting as showing that he continued to make use of the analogy
between slavery and property which we have seen in the Fathers. 'A
thing is said to belong to the natural law in two ways. First,
because nature inclines thereto, _e.g._ that one