On Christian Doctrine

56. Coming now to the science of number, it is clear to the dullest apprehension that this was not created by man, but was discovered by investigation. For, though Virgil could at his own pleasure make the first syllable of Italia long, while the ancients pronounced it short, it is not in any man’s power to determine at his pleasure that three times three are not nine, or do not make a square, or are not the triple of three, nor one and a half times the number six, or that it is not true that they are not the double of any number because odd numbers have no half. Whether, then, numbers are considered in themselves, or as applied to the laws of figures, or of sounds, or of other motions, they have fixed laws which were not made by man, but which the acuteness of ingenious men brought to light.

57. The man, however, who puts so high a value on these things as to be inclined to boast himself one of the learned, and who does not rather inquire after the source from which those things which he perceives to be true derive their truth, and from which those others which he perceives to be unchangeable also derive their truth and unchangeableness, and who, mounting up from bodily appearances to the mind of man, and finding that it too is changeable (for it is sometimes instructed, at other times uninstructed), although it holds a middle place between the unchangeable truth above it and the changeable things beneath it, does not strive to make all things redound to the praise and love of the one God from whom he knows that all things have their being;—the man, I say, who acts in this way may seem to be learned, but wise he cannot in any sense be deemed.