Therefore all beings apart from God are not their own being, but are beings by participation. Therefore it must be that all things which are diversified by the diverse participation of being, so as to be more or less perfect, are caused by one First Being, Who possesses being most perfectly.
 Thomas Aquinas, Summa Theologica (1274). copy citation

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Author Thomas Aquinas
Source Summa Theologica
Topic God participation
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

“Now it has been shown above (Q. 3, A. 4) when treating of the divine simplicity that God is the essentially self-subsisting Being; and also it was shown (Q. 11, AA. 3, 4) that subsisting being must be one; as, if whiteness were self-subsisting, it would be one, since whiteness is multiplied by its recipients. Therefore all beings apart from God are not their own being, but are beings by participation. Therefore it must be that all things which are diversified by the diverse participation of being, so as to be more or less perfect, are caused by one First Being, Who possesses being most perfectly. Hence Plato said (Parmen. xxvi) that unity must come before multitude; and Aristotle said (Metaph. ii, text 4) that whatever is greatest in being and greatest in truth, is the cause of every being and of every truth; just as whatever is the greatest in heat is the cause of all heat.
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