For an individual man cannot be the cause of human nature absolutely, because he would then be the cause of himself
 Thomas Aquinas, Summa Theologica (1274). copy citation

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Author Thomas Aquinas
Source Summa Theologica
Topic human nature cause
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

“and thus it requires in its action some pre-existing thing, which can be touched or moved, which is contrary to the very idea of creation. Reply Obj. 1: A perfect thing participating any nature, makes a likeness to itself, not by absolutely producing that nature, but by applying it to something else. For an individual man cannot be the cause of human nature absolutely, because he would then be the cause of himself; but he is the cause of human nature being in the man begotten; and thus he presupposes in his action a determinate matter whereby he is an individual man. But as an individual man participates human nature, so every created being participates, so to speak, the nature of being;” source