Just as a thing may be apprehended as good, when it is not truly good; so a thing may be apprehended as evil, whereas it is not truly evil. Hence it happens sometimes that neither hatred of evil nor love of good is good.
 Thomas Aquinas, Summa Theologica (1274). copy citation

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Author Thomas Aquinas
Source Summa Theologica
Topic evil love
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

“But being, inasmuch as it is this determinate being, has an aspect of repugnance to some determinate being. And in this way, one being is hateful to another, and is evil; though not in itself, but by comparison with something else. Reply Obj. 2: Just as a thing may be apprehended as good, when it is not truly good; so a thing may be apprehended as evil, whereas it is not truly evil. Hence it happens sometimes that neither hatred of evil nor love of good is good. Reply Obj. 3: To different things the same thing may be lovable or hateful: in respect of the natural appetite, owing to one and the same thing being naturally suitable to one thing, and naturally unsuitable to another:” source