An injury inflicted on a person connected with others is less harmful to the persons with whom he is connected, than if it were perpetrated immediately on them, and from this point of view it is a less grievous sin. But all that belongs to the injury of the person with whom he is connected, is added to the sin of which a man is guilty through injuring the other one in himself.
 Thomas Aquinas, Summa Theologica (1274). copy citation

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Author Thomas Aquinas
Source Summa Theologica
Topic sin injury
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

“It may happen, however, that in view of certain circumstances, a sin committed against one who is not connected with any other person, is more grievous, on account of either the dignity of the person, or the greatness of the injury. Reply Obj. 1: An injury inflicted on a person connected with others is less harmful to the persons with whom he is connected, than if it were perpetrated immediately on them, and from this point of view it is a less grievous sin. But all that belongs to the injury of the person with whom he is connected, is added to the sin of which a man is guilty through injuring the other one in himself. Reply Obj. 2: Injuries done to widows and orphans are more insisted upon both through being more opposed to mercy, and because the same injury done to such persons is more grievous to them since they have no one to turn to for relief.” source