because what a man does in ignorance, he does accidentally.
 Thomas Aquinas, Summa Theologica (1274). copy citation

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Author Thomas Aquinas
Source Summa Theologica
Topic ignorance
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 mode of virtue consists in three things, as the Philosopher states in Ethic. ii. The first is that man should act "knowingly": and this is subject to the judgment of both Divine and human law; because what a man does in ignorance, he does accidentally. Hence according to both human and Divine law, certain things are judged in respect of ignorance to be punishable or pardonable. The second point is that a man should act "deliberately," i.e. "from choice, choosing that particular action for its own sake";” source