Obj. 2: Further, virtue denotes a certain perfection of power. But vice does not denote anything relative to power. Therefore vice is not contrary to virtue.
 Thomas Aquinas, Summa Theologica (1274). copy citation

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Author Thomas Aquinas
Source Summa Theologica
Topic perfection vice
Date 1274
Language English
Reference
Note Translated by Fathers of the English Dominican Province
Weblink http://www.gutenberg.org/cache/epub/17897/pg17897-images.html

Context

“For one thing has one contrary, as proved in Metaph. x, text. 17. Now sin and malice are contrary to virtue. Therefore vice is not contrary to it: since vice applies also to undue disposition of bodily members or of any things whatever.
Obj. 2: Further, virtue denotes a certain perfection of power. But vice does not denote anything relative to power. Therefore vice is not contrary to virtue. Obj. 3: Further, Cicero (De Quaest. Tusc. iv) says that "virtue is the soul's health." Now sickness or disease, rather than vice, is opposed to health. Therefore vice is not contrary to virtue.
On the contrary, Augustine says (De Perfect.” source