Now it is evident that the rectitude of human reason is compared to the Divine Reason, as a lower motive principle to a higher: for the Eternal Reason is the supreme rule of all human rectitude.
 Thomas Aquinas, Summa Theologica (1274). copy citation

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Author Thomas Aquinas
Source Summa Theologica
Topic reason rectitude
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

“Therefore they correspond to one another.
I answer that, A lower principle of movement is helped chiefly, and is perfected through being moved by a higher principle of movement, as a body through being moved by a spirit. Now it is evident that the rectitude of human reason is compared to the Divine Reason, as a lower motive principle to a higher: for the Eternal Reason is the supreme rule of all human rectitude. Consequently prudence, which denotes rectitude of reason, is chiefly perfected and helped through being ruled and moved by the Holy Ghost, and this belongs to the gift of counsel, as stated above (A. 1).” source