A good passion consequent to the judgment of reason increases merit; but if it precede, so that a man is moved to do well, rather by his passion than by the judgment of his reason, such a passion diminishes the goodness and praiseworthiness of his action.
 Thomas Aquinas, Summa Theologica (1274). copy citation

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Author Thomas Aquinas
Source Summa Theologica
Topic goodness action
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 the gravity of a sin is measured on the part of that from which he turns, which results accidentally from his turning to something else—accidentally, i.e. beside his intention. Now an effect is increased by the increase, not of its accidental cause, but of its direct cause. Reply Obj. 2: A good passion consequent to the judgment of reason increases merit; but if it precede, so that a man is moved to do well, rather by his passion than by the judgment of his reason, such a passion diminishes the goodness and praiseworthiness of his action. Reply Obj. 3: Although the movement of the will incited by the passion is more intense, yet it is not so much the will's own movement, as if it were moved to sin by the reason alone. ________________________” source