The most perfect knowledge, if it is not supported by the most perfect self-command, will not always enable him to do his duty.
 Adam Smith, The Theory of Moral Sentiments (1759). copy citation

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Author Adam Smith
Source The Theory of Moral Sentiments
Topic duty support
Date 1759
Language English
Reference
Note
Weblink https://en.wikisource.org/wiki/The_Theory_of_Moral_Sentiments

Context

“But the most perfect knowledge of those rules will not alone enable him to act in this manner: his own passions are very apt to mislead him; sometimes to drive him and sometimes to seduce him to violate all the rules which he himself, in all his sober and cool hours, approves of. The most perfect knowledge, if it is not supported by the most perfect self-command, will not always enable him to do his duty. Some of the best of the ancient moralists seem to have considered those passions as divided into two different classes: first, into those which it requires a considerable exertion of self-command to restrain even for a single moment;” source