Summa Theologica, by St. Thomas Aquinas, , at sacred-texts.com
We must now consider cruelty, under which head there are two
points of inquiry: (1) Whether cruelty is opposed to clemency?
(2) Of its comparison with savagery or brutality. Objection 1:
It would seem that cruelty is not opposed to clemency. For
Seneca says (De Clementia ii, 4) that "those are said to be
cruel who exceed in punishing," which is contrary to justice.
Now clemency is reckoned a part, not of justice but of
temperance. Therefore apparently cruelty is not opposed to
clemency. Objection 2: Further, it is written (Jer. 6:23): "They
are cruel, and will have no mercy"; so that cruelty would seem
opposed to mercy. Now mercy is not the same as clemency, as
stated above (Q, A, ad 3). Therefore cruelty is not opposed to
clemency. Objection 3: Further, clemency is concerned with the
infliction of punishment, as stated above (Q, A): whereas
cruelty applies to the withdrawal of beneficence, according to
Prov. 11:17, "But he that is cruel casteth o