You will finally discover that the world was not conceived by chance and without reason, but for an useful end, and for the great advantage of all beings, since it is really the school where reasonable souls exercise themselves, the training ground where they learn to know God; since by the sight of visible and sensible things the mind is led, as by a hand, to the contemplation of invisible things. “For,” as the Apostle says, “the invisible things of him from the creation of the world are clearly seen, being understood by the things that are made” (Rom. 1:20).

The Hexaemeron (The Six Days of Creation)