The cause of honor is that by reason of which the person honored has a certain excellence, for honor is reverence given to something on account of its excellence, as stated in the Second Part (II-II, Q. 103, A. 1).
 Thomas Aquinas, Summa Theologica (1274). copy citation

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Author Thomas Aquinas
Source Summa Theologica
Topic honor reverence
Date 1274
Language English
Reference
Note Translated by Fathers of the English Dominican Province
Weblink http://www.gutenberg.org/cache/epub/19950/pg19950-images.html

Context

“And if at any time it happen that we speak of honoring a man's hand or foot, it is not by reason of these members being honored of themselves: but by reason of the whole being honored in them. In this way a man may be honored even in something external; for instance in his vesture, his image, or his messenger.
The cause of honor is that by reason of which the person honored has a certain excellence, for honor is reverence given to something on account of its excellence, as stated in the Second Part (II-II, Q. 103, A. 1). If therefore in one man there are several causes of honor, for instance, rank, knowledge, and virtue, the honor given to him will be one in respect of the person honored, but several in respect of the causes of honor: for it is the man that is honored, both on account of knowledge and by reason of his virtue.
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