A natural body is moved to its own being by its substantial form
 Thomas Aquinas, Summa Theologica (1274). copy citation

add
Author Thomas Aquinas
Source Summa Theologica
Topic body
Date 1274
Language English
Reference
Note Translated by Fathers of the English Dominican Province
Weblink http://www.gutenberg.org/cache/epub/17611/pg17611-images.html

Context

“Consequently intellect and will must necessarily be different powers in every creature. It is not so with God, for He has within Himself universal being, and the universal good. Therefore both intellect and will are His nature. Reply Obj. 1: A natural body is moved to its own being by its substantial form: while it is inclined to something outside by something additional, as has been said. Reply Obj. 2: Faculties are not differentiated by any material difference of their objects, but according to their formal distinction, which is taken from the nature of the object as such.” source