Existence in nature does not belong to primary matter, which is a potentiality, unless it is reduced to act by a form.
 Thomas Aquinas, Summa Theologica (1274). copy citation

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Author Thomas Aquinas
Source Summa Theologica
Topic existence acts
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

“On the other hand, the divine intellect, which is no way in potentiality, is not perfected by the intelligible object, nor is it assimilated thereto, but is its own perfection, and its own intelligible object. Reply Obj. 3: Existence in nature does not belong to primary matter, which is a potentiality, unless it is reduced to act by a form. Now our passive intellect has the same relation to intelligible objects as primary matter has to natural things; for it is in potentiality as regards intelligible objects, just as primary matter is to natural things.” source