For there is an evil which can be present to the virtuous man, as we have just stated; which evil is rejected by reason. Wherefore the sensitive appetite follows reason's rejection by sorrowing for that evil; yet moderately, according as reason dictates.
 Thomas Aquinas, Summa Theologica (1274). copy citation

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Author Thomas Aquinas
Source Summa Theologica
Topic rejection evil
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

“Now the enjoyment of a good possessed, or the desire to have good that one possesses not, may be consistent with virtue: but depression of the mind resulting from sorrow for a present evil, is altogether contrary to reason: wherefore it is incompatible with virtue. But this is unreasonable. For there is an evil which can be present to the virtuous man, as we have just stated; which evil is rejected by reason. Wherefore the sensitive appetite follows reason's rejection by sorrowing for that evil; yet moderately, according as reason dictates. Now it pertains to virtue that the sensitive appetite be conformed to reason, as stated above (A. 1, ad 2). Wherefore moderated sorrow for an object which ought to make us sorrowful, is a mark of virtue; as also the Philosopher says (Ethic. ii, 6, 7) .” source