Commenting on Hebrews 11:3 St. Thomas notes:
… it must be known that the Word of God is the very concept of God, by which He understands Himself and other things. We see this when an artisan, producing something outside himself, makes it unto the likeness of his concept …. Since the whole creation is perfectly disposed, as produced by an artisan, in Whom error cannot occur, nor any other defect, then it most fully corresponds to the divine concept according to its own mode … Therefore, he says, “By faith we understand that the world”, that is, the whole entirety of creation, “was framed”, that is, conveniently corresponding, “to the Word”, that is, to the concept of God, as the thing made is to its art.
Aquinas then briefly discusses the opinion of the ancients, Anaxagorus, Plato, etc: that visible things are copies of the Ideas, and others said the visible is from the Intelligence.
But we say according to the aforesaid mode that from the invisible rational ideas in the Word of God, through Whom all things were made, the visible things were produced. These ideas, even if they are the same really, yet from the perspective of the creature differ according to reason by diverse signified respects. Hence, by one notion man was made, and by another the horse, as Augustine says in the book 83 Questions. So then, “the world was framed to the Word of God”, such “that from the invisible” rational ideas in the Word of God “the visible things”, that is, every creature, “might be made.”
It is interesting to see Thomas’s biblical justification for his conception of universal principles. The ideas for all created things come from the Word who is God’s very conception of himself. Therefore when God extends his work ad extra in creating he is placing the image of his Word upon those things just as an artist places his art upon whatever he makes. Even horses and trees have their exemplar cause in the Word of God. Also, these ideas of “horse” and “man” etc. are all one idea in the Word but are differentiated within creation from man’s perspective. Therefore, all esse commune (created being) has its universal principle or idea in God’s eternally begotten Son. According to Catherine Pickstock this level of being plays a significant role in Thomas’s Eucharistic theology. These invisible things, of which St. Paul writes, are not discerned by natural theology but by faith because “divine authority makes this choice through which the intellect is determined, so that it adheres firmly to those things which are of faith and assents to them most certainly.” (Ibid)