Wherefore if a man, in self-defense, uses more than necessary violence, it will be unlawful
 Thomas Aquinas, Summa Theologica (1274). copy citation

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Author Thomas Aquinas
Source Summa Theologica
Topic violence defense
Date 1274
Language English
Reference
Note Translated by Fathers of the English Dominican Province
Weblink http://www.gutenberg.org/cache/epub/18755/pg18755-images.html

Context

“Therefore this act, since one's intention is to save one's own life, is not unlawful, seeing that it is natural to everything to keep itself in being, as far as possible. And yet, though proceeding from a good intention, an act may be rendered unlawful, if it be out of proportion to the end. Wherefore if a man, in self-defense, uses more than necessary violence, it will be unlawful: whereas if he repel force with moderation his defense will be lawful, because according to the jurists [*Cap. Significasti, De Homicid. volunt. vel casual.] , "it is lawful to repel force by force, provided one does not exceed the limits of a blameless defense."” source