Nicene and Post-Nicene Fathers, Vol. IV:
Writings in Connection with the Manichæan Controversy.: Chapter 19

Chapter 19.—If the Mind Has No Material Extension, Much Less Has God.

21.  So then, if the mind, so liable to change, whether from a multitude of dissimilar desires, or from feelings varying according to the abundance or the want of desirable things, or from these endless sports of the fancy, or from forgetfulness and remembrance, or from learning and ignorance; if the mind, I say, exposed to frequent change from these and the like causes, is perceived to be without any local or material extension, and to have a vigor of action which surmounts these material conditions, what must we think or conclude of God Himself, who remains superior to all intelligent beings in His freedom from perturbation and from change, giving to every one what is due?  Him the mind dares to express more easily than to see; and the clearer the sight, the less is the power of expression.  And yet this God, if, as the Manichæan fables are constantly asserting, He were limited in extension in one direction and unlimited in others, could be measured by so many subdivisions or fractions of greater or less size, as every one might fancy; so that, for example, a division of the extent of two feet would be less by eight parts than one of ten feet.  For this is the property of all natures which have extension in space, and therefore cannot be all in one place.  But even with the mind this is not the case; and this degrading and perverted idea of the mind is found among people who are unfit for such investigations.