Lesson Fifteen in Introduction to Thomistic Philosophy, with Fr Thomas Joseph White, OP, DPhil (Oxon), STL, Rector of the Pontifical University of Saint Thomas Aquinas in Rome.
Everything that exists in some way has being, is good, has a kind of unity to it, and a truth or intelligibility. But what about the source of all that exists?
If God is the cause of all that exists, then the effects of must in some way resemble the cause. If things in the world have goodness within them, this must in some way reflect, however imperfectly, the goodness of God. From this way of thinking you can begin to speak about an analogy between creatures and God.