For just as the higher a man's position is, the more undeservedly he is despised; so the lower it is, the less reason he has for despising. Thus a nobleman is angry if he be insulted by a peasant; a wise man, if by a fool; a master, if by a servant.
If, however, the littleness or deficiency lessens the unmerited contempt, then it does not increase but lessens anger.
 Thomas Aquinas, Summa Theologica (1274). copy citation

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Author Thomas Aquinas
Source Summa Theologica
Topic anger littleness
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

“unmerited contempt more than anything else is a provocative of anger. Consequently deficiency or littleness in the person with whom we are angry, tends to increase our anger, in so far as it adds to the unmeritedness of being despised. For just as the higher a man's position is, the more undeservedly he is despised; so the lower it is, the less reason he has for despising. Thus a nobleman is angry if he be insulted by a peasant; a wise man, if by a fool; a master, if by a servant. If, however, the littleness or deficiency lessens the unmerited contempt, then it does not increase but lessens anger. In this way those who repent of their ill-deeds, and confess that they have done wrong, who humble themselves and ask pardon, mitigate anger, according to Prov. 15:1: "A mild answer breaketh wrath":” source