The love of charity takes its quantity not only from its object which is God, but also from the lover, who is the man that has charity, even as the quantity of any action depends in some way on the subject.
 Thomas Aquinas, Summa Theologica (1274). copy citation

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Author Thomas Aquinas
Source Summa Theologica
Topic action love
Date 1274
Language English
Reference
Note Translated by Fathers of the English Dominican Province
Weblink http://www.gutenberg.org/cache/epub/18755/pg18755-images.html

Context

“Therefore man, out of charity, ought to love himself more than his neighbor: in sign whereof, a man ought not to give way to any evil of sin, which counteracts his share of happiness, not even that he may free his neighbor from sin. Reply Obj. 1: The love of charity takes its quantity not only from its object which is God, but also from the lover, who is the man that has charity, even as the quantity of any action depends in some way on the subject. Wherefore, though a better neighbor is nearer to God, yet because he is not as near to the man who has charity, as this man is to himself, it does not follow that a man is bound to love his neighbor more than himself.” source