City of God

As for their other assertion, that God's knowledge cannot comprehend things infinite, it only remains for them to affirm, in order that they may sound the depths of their impiety, that God does not know all numbers. For it is very certain that they are infinite; since, no matter of what number you suppose an end to be made, this number can be, I will not say, increased by the addition of one more, but however great it be, and however vast be the multitude of which it is the rational and scientific expression, it can still be not only doubled, but even multiplied.

Moreover, each number is so defined by its own properties, that no two numbers are equal. They are therefore both unequal and different from one another; and while they are simply finite, collectively they are infinite. Does God, therefore, not know numbers on account of this infinity; and does His knowledge extend only to a certain height in numbers, while of the rest He is ignorant? Who is so left to himself as to say so? Yet they can hardly pretend to put numbers out of the question, or maintain that they have nothing to do with the knowledge of God; for Plato, their great authority, represents God as framing the world on numerical principles: and in our books also it is said to God, “You have ordered all things in number, and measure, and weight.” The prophet also says, Who brings out their host by number. And the Saviour says in the Gospel, “The very hairs of your head are all numbered.” Far be it, then, from us to doubt that all number is known to Him “whose understanding,” according to the Psalmist, “is infinite.” The infinity of number, though there be no numbering of infinite numbers, is yet not incomprehensible by Him whose understanding is infinite. And thus, if everything which is comprehended is defined or made finite by the comprehension of him who knows it, then all infinity is in some ineffable way made finite to God, for it is comprehensible by His knowledge. Wherefore, if the infinity of numbers cannot be infinite to the knowledge of God, by which it is comprehended, what are we poor creatures that we should presume to fix limits to His knowledge, and say that unless the same temporal thing be repeated by the same periodic revolutions, God cannot either foreknow His creatures that He may make them, or know them when He has made them? God, whose knowledge is simply manifold, and uniform in its variety, comprehends all incomprehensibles with so incomprehensible a comprehension, that though He willed always to make His later works novel and unlike what went before them, He could not produce them without order and foresight, nor conceive them suddenly, but by His eternal foreknowledge.