The Peripatetic axiom is: "Nothing is in the intellect that was not first in the senses" (Latin: Nihil est in intellectu quod non sit prius in sensu). It is found in De veritate, q. 2 a. 3 arg. 19 by Thomas Aquinas.^[1]

Aquinas adopted this principle from the Peripatetic school of Greek philosophy, established by Aristotle.^[where?] Aquinas argued that the existence of God could be proved by reasoning from sense data.^[2] He used a variation on the Aristotelian notion of the "active intellect" (Latin: intellectus agens)^[3] which he interpreted as the ability to abstract universal meanings from particular empirical data.^[4]