Objection 1: It seems that ingratitude is not a special sin. For whoever sins acts against God his sovereign benefactor. But this pertains to ingratitude. Therefore ingratitude is not a special sin.
 Thomas Aquinas, Summa Theologica (1274). copy citation

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Author Thomas Aquinas
Source Summa Theologica
Topic ingratitude sin
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

“Hence that anyone should owe this debt unwillingly seems to arise from lack of love for his benefactor. _______________________
SECOND ARTICLE [II-II, Q. 107, Art. 2]
Whether Ingratitude Is a Special Sin?
Objection 1: It seems that ingratitude is not a special sin. For whoever sins acts against God his sovereign benefactor. But this pertains to ingratitude. Therefore ingratitude is not a special sin. Obj. 2: Further, no special sin is contained under different kinds of sin. But one can be ungrateful by committing different kinds of sin, for instance by calumny, theft, or something similar committed against a benefactor.” source