when a man rejoices with the joyful, and when he sorrows with the sorrowful.
 Thomas Aquinas, Summa Theologica (1274). copy citation

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Author Thomas Aquinas
Source Summa Theologica
Topic sorrow
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, since every pleasure assuages sorrow, as stated above (A. 1) , it follows that sorrow is mitigated by a sympathizing friend. Reply Obj. 1: In either case there is a proof of friendship, viz. when a man rejoices with the joyful, and when he sorrows with the sorrowful. Consequently each becomes an object of pleasure by reason of its cause. Reply Obj. 2: The friend's sorrow itself would be a cause of sorrow: but consideration of its cause, viz. his love, gives rise rather to pleasure.” source