Therefore it seems that perseverance is a part not of a moral virtue, but rather of prudence which perfects the reason.
 Thomas Aquinas, Summa Theologica (1274). copy citation

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Author Thomas Aquinas
Source Summa Theologica
Topic perseverance prudence
Date 1274
Language English
Reference
Note Translated by Fathers of the English Dominican Province
Weblink http://www.gutenberg.org/cache/epub/18755/pg18755-images.html

Context

“2: Further, every part of a moral virtue is about certain passions which that virtue moderates. Now perseverance does not imply moderation of the passions: since the more violent the passions, the more praiseworthy is it to persevere in accordance with reason. Therefore it seems that perseverance is a part not of a moral virtue, but rather of prudence which perfects the reason. Obj. 3: Further, Augustine says (De Persev. i) that no one can lose perseverance; whereas one can lose the other virtues. Therefore perseverance is greater than all the other virtues. Now a principal virtue is greater than its part.” source