Thomas Aquinas, in his explanation of his doctrine of Analogy in Summa Contra Gentiles I.28, points out that “perfection” must be understood at least somewhat differently when applied to God than when applied to creatures. Yet, he recognizes that Jesus calls his disciples to nevertheless aim to close that gap (Mt. 5:48). Thomas says that the fundamental divide between how we would use the word perfect differently between God and creation is found in the fact of creation. Existence is itself the most foundational prerequisite for perfection, and because God has always, eternally existed (as opposed to all other things which had a beginning), He is by definition “most perfect.”
I was initially a little skeptical about this description of God as “most perfect.” Was he trying to put God and creation on some kind of continuum? But as I considered what Thomas is up to, it rather appears that he is trying to figure out how and in what ways creatures are like their Creator. He seems to conclude that the act of creation is where we find the first likeness of creation to its Creator. Because God created the world from nothing and thereby brought being from non-being, he has in the most basic sense made the world to be just as he is from all eternity. The gift of being is fundamentally a sort of likeness that all of creation has with God who always and eternally exists.
Thomas knows that in order for language to work it must find its origin and meaning ultimately in the person and life of God. Creation must be like God in various ways in order for words to have meaning. And he recognizes that in the most fundamental sense, a leaf is like God because it exists just like God exists. It participates in the life of the Triune God if only as a result of the Word of God which spoke and pushed certain nutrients up through the veins of a particular Oak tree and eventually burst out of some happy petiole on the end of some branch waving at the world. Existence is itself a wonderful gift, and it is the gift of being, tasting if only briefly what God knows in eternity.