A man is said to be a fool if he judges wrongly about the common end of life, wherefore folly is properly opposed to wisdom, which makes us judge aright about the universal cause.
 Thomas Aquinas, Summa Theologica (1274). copy citation

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Author Thomas Aquinas
Source Summa Theologica
Topic wisdom life
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

“For dulness is contrary to sharpness, since an intellect is said, by comparison, to be sharp, when it is able to penetrate into the heart of the things that are proposed to it. Hence it is dulness of mind that renders the mind unable to pierce into the heart of a thing. A man is said to be a fool if he judges wrongly about the common end of life, wherefore folly is properly opposed to wisdom, which makes us judge aright about the universal cause. Ignorance implies a defect in the mind, even about any particular things whatever, so that it is contrary to knowledge, which gives man a right judgment about particular causes, viz. about creatures.” source