Reply Obj. 3: Immoderate sorrow is a disease of the mind: but moderate sorrow is the mark of a well-conditioned mind, according to the present state of life.
 Thomas Aquinas, Summa Theologica (1274). copy citation

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Author Thomas Aquinas
Source Summa Theologica
Topic sorrow present
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 there is no room for sorrow in the blessed, in whom there can be no hindrance to wisdom.
Reply Obj. 2: Sorrow hinders the work that makes us sorrowful: but it helps us to do more readily whatever banishes sorrow.
Reply Obj. 3: Immoderate sorrow is a disease of the mind: but moderate sorrow is the mark of a well-conditioned mind, according to the present state of life. ________________________
FOURTH ARTICLE [I-II, Q. 59, Art. 4]
Whether All the Moral Virtues Are About the Passions?
Objection 1: It would seem that all the moral virtues are about the passions. For the Philosopher says (Ethic. ii, 3) that "moral virtue is about objects of pleasure and sorrow." But pleasure and sorrow are passions, as stated above (Q.” source