Augustine on Miracles, from The City of God

For we cannot listen to those who maintain that the invisible God works no visible miracles; for even they believe that He made the world, which surely they will not deny to be visible. Whatever marvel happens in this world, it is certainly less marvellous than this whole world itself,—I mean the sky and earth, and all that is in them,—and these God certainly made. But, as the Creator Himself is hidden and incomprehensible to man, so also is the manner of creation. Although, therefore, the standing miracle of this visible world is little thought of, because always before us, yet, when we arouse ourselves to contemplate it, it is a greater miracle than the rarest and most unheard-of marvels. For man himself is a greater miracle than any miracle done through his instrumentality. Therefore God, who made the visible heaven and earth, does not disdain to work visible miracles in heaven or earth, that He may thereby awaken the soul which is immersed in things visible to worship Himself, the Invisible. But the place and time of these miracles are dependent on His unchangeable will, in which things future are ordered as if already they were accomplished. For He moves things temporal without Himself moving in time. - Augustine, The City of God, Tenth Book, 12, public domain. Available from Project Gutenberg, and other sources.