From Augustine to Volusianus
"God is not said to fill the world in the same way as water, air, and even light occupy space, so that with a greater or smaller part of Himself He occupies a greater or smaller part of the world. He is able to be everywhere present in the entirety of His being: He cannot be confined in any place: He can come without leaving the place where He was: He can depart without forsaking the place to which He had come.
The mind of man wonders at this, and because it cannot comprehend it, refuses, perhaps, to believe it. I,et it, however, not go on to wonder incredulously at the attributes of the Deity without first wondering in like manner at the mysteries within itself; let it, if possible, raise itself for a little above the body, and above those things which it is accustomed to perceive by the bodily organs, and let it contemplate what that is which uses the body as its instrument."
Augustine, Letters, II, 137,4-5 (to Volusianus)