Those who are quick-tempered do not hide their anger; wherefore the harm they do others is not so sudden, as not to be foreseen.
 Thomas Aquinas, Summa Theologica (1274). copy citation

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Author Thomas Aquinas
Source Summa Theologica
Topic anger hiding
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

“Consequently whatever increases a man's power, is of a nature to increase hope, and, for the same reason, to diminish fear, since fear is about an evil which cannot be easily repelled. Since, therefore, experience increases a man's power of action, therefore, as it increases hope, so does it diminish fear. Reply Obj. 2: Those who are quick-tempered do not hide their anger; wherefore the harm they do others is not so sudden, as not to be foreseen. On the other hand, those who are gentle or cunning hide their anger; wherefore the harm which may be impending from them, cannot be foreseen, but takes one by surprise. For this reason the Philosopher says that such men are feared more than others.” source