The intellect is moved, of necessity, by an object which is such as to be always and necessarily true
 Thomas Aquinas, Summa Theologica (1274). copy citation

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Author Thomas Aquinas
Source Summa Theologica
Topic necessity intellect
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

“The sufficient mover of a power is none but that object that in every respect presents the aspect of the mover of that power. If, on the other hand, it is lacking in any respect, it will not move of necessity, as stated above. Reply Obj. 2: The intellect is moved, of necessity, by an object which is such as to be always and necessarily true: but not by that which may be either true or false—viz. by that which is contingent: as we have said of the good. Reply Obj. 3: The last end moves the will necessarily, because it is the perfect good.” source