Reply Obj. 3: Increase in intensity is in proportion to the nature of a thing. And as the form is a perfection, so privation removes a perfection. Hence every form, perfection, and good is intensified by approach to the perfect term; but privation and evil by receding from that term.
 Thomas Aquinas, Summa Theologica (1274). copy citation

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Author Thomas Aquinas
Source Summa Theologica
Topic perfection intensity
Date 1274
Language English
Reference
Note Translated by Fathers of the English Dominican Province
Weblink http://www.gutenberg.org/cache/epub/17611/pg17611-images.html

Context

“Hence, since evil is privation of good, as appears from what was said above (Q. 48, AA. 1, 2, 3) , it is opposed to that good which has some potentiality, but not to the supreme good, who is pure act.
Reply Obj. 3: Increase in intensity is in proportion to the nature of a thing. And as the form is a perfection, so privation removes a perfection. Hence every form, perfection, and good is intensified by approach to the perfect term; but privation and evil by receding from that term. Hence a thing is not said to be evil and worse, by reason of access to the supreme evil, in the same way as it is said to be good and better, by reason of access to the supreme good.
Reply Obj. 4: No being is called evil by participation, but by privation of participation.” source