Obj. 3: Further, Damascene says (De Fide Orth. ii, 22) that passion is a movement. But love does not imply the movement of the appetite; for this is desire, of which movement love is the principle. Therefore love is not a passion.
 Thomas Aquinas, Summa Theologica (1274). copy citation

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Author Thomas Aquinas
Source Summa Theologica
Topic passion love
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

“Therefore love is not a passion.
Obj. 2: Further, love is a kind of union or bond, as Augustine says (De Trin. viii, 10) . But a union or bond is not a passion, but rather a relation. Therefore love is not a passion.
Obj. 3: Further, Damascene says (De Fide Orth. ii, 22) that passion is a movement. But love does not imply the movement of the appetite; for this is desire, of which movement love is the principle. Therefore love is not a passion. On the contrary, The Philosopher says (Ethic. viii, 5) that "love is a passion."
I answer that, Passion is the effect of the agent on the patient. Now a natural agent produces a twofold effect on the patient: for in the first place it gives it the form; and secondly it gives it the movement that results from the form.” source