It is not sufficient to say, "God spake and it was so." For the natures of things that are created ought to harmonise with the commands of God. I will say more clearly what I mean. Did God ordain that fire should mount upwards by chance and earth sink down? Was it not necessary, in order that the ordinance of God should be fulfilled, for the former to be light and the latter to weigh heavy? And in the case of other things also this is equally true.

Against the Galilaeans (c. 362)