For nothing swells the anger more, than when a good man is detected of villainy, or one who we thought loved us falls out and jangles with us.
 Plutarch, Moralia (c. 100 AD). copy citation

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Author Plutarch
Source Moralia
Topic anger love
Date c. 100 AD
Language English
Reference
Note Translated by Arthur Richard Shilleto
Weblink http://www.gutenberg.org/files/23639/23639-h/23639-h.htm

Context

“Moreover those to whom it happens through their genuine hatred of what is bad to be frequently overtaken by anger, can abate its excess and acerbity by giving up their excessive confidence in their intimates. For nothing swells the anger more, than when a good man is detected of villainy, or one who we thought loved us falls out and jangles with us. As for my own disposition, you know of course how mightily it inclines to goodwill and belief in mankind. As then people walking on empty space,706 the more confidently I believe in anybody's affection, the more sorrow and distress do I feel if my estimate is a mistaken one.” source