We are sometimes under a greater obligation to one who has given little with a large heart, and has bestowed a small favor, yet willingly.
 Thomas Aquinas, Summa Theologica (1274). copy citation

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Author Thomas Aquinas
Source Summa Theologica
Topic heart obligation
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

“Further, no one can consider what he does not know. Now God alone knows the interior disposition. Therefore it is impossible to repay a favor according to the benefactor's disposition. On the contrary, Seneca says (De Benef. i) : "We are sometimes under a greater obligation to one who has given little with a large heart, and has bestowed a small favor, yet willingly." I answer that, The repayment of a favor may belong to three virtues, namely, justice, gratitude and friendship. It belongs to justice when the repayment has the character of a legal debt, as in a loan and the like:” source