Accordingly for a man to do a good deed, it is requisite not only that his reason be well disposed by means of a habit of intellectual virtue; but also that his appetite be well disposed by means of a habit of moral virtue.
 Thomas Aquinas, Summa Theologica (1274). copy citation

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Author Thomas Aquinas
Source Summa Theologica
Topic virtue reason
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

“And in this way, there is some truth in the saying of Socrates that so long as a man is in possession of knowledge he does not sin: provided, however, that this knowledge is made to include the use of reason in this individual act of choice.
Accordingly for a man to do a good deed, it is requisite not only that his reason be well disposed by means of a habit of intellectual virtue; but also that his appetite be well disposed by means of a habit of moral virtue. And so moral differs from intellectual virtue, even as the appetite differs from the reason. Hence just as the appetite is the principle of human acts, in so far as it partakes of reason, so are moral habits to be considered virtues in so far as they are in conformity with reason.
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