Reply Obj. 2: Passion is an effect of action. Hence it is reasonable that the first passive principle should be the effect of the first active principle, since every imperfect thing is caused by one perfect. For the first principle must be most perfect, as Aristotle says (Metaph. xii, text 40) .
 Thomas Aquinas, Summa Theologica (1274). copy citation

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Author Thomas Aquinas
Source Summa Theologica
Topic action passion
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

“But here we are speaking of things according to their emanation from the universal principle of being; from which emanation matter itself is not excluded, although it is excluded from the former mode of being made.
Reply Obj. 2: Passion is an effect of action. Hence it is reasonable that the first passive principle should be the effect of the first active principle, since every imperfect thing is caused by one perfect. For the first principle must be most perfect, as Aristotle says (Metaph. xii, text 40) . Reply Obj. 3: The reason adduced does not show that matter is not created, but that it is not created without form; for though everything created is actual, still it is not pure act. Hence it is necessary that even what is potential in it should be created, if all that belongs to its being is created.” source