(17) Who are the Kenites, the Kenezites, and the Kadmonites, and the Hittites, and the Perizzites, and the Rephaims, and the Amorites, the Canaanites, the Girgashites, and the Jebusites? (#Ge 15:20). Ten nations of wickedness are here enumerated, which he here destroys because of their neighbourhood, since the number ten, when false and improperly stamped, is very near to that which is good and an object of affection; but the complete perfection of the number ten is exceedingly fit, as being the measure of infinite numbers, since the world is arranged in accordance with it, and so likewise is the mind of the wise man, the substance of which, nevertheless, wickedness perverts and overthrows, despising all very necessary powers, so that that alone remains which the sacred writer has said, namely, that the pursuit of virtue is a blessing, for the wicked man is such that he embraces vague opinions rather than truth, and of such is Ishmael, though the seed of the prophets.
(18) Why it was that Sarah, the wife of Abraham, bore him no children? (#Ge 16:1). The mother of opinion is here spoken of as barren. In the first place in order that the son of generation might appear more wonderful, as being born by a miracle. In the second place in order that his conception and nativity might appear to be owing not more to the marriage of the man than to divine providence. For it is not owing to the faculty of conception that a barren woman should bear a son, but rather to the operation of divine power. This is the literal meaning of the statement. But if we look to its inward sense, then we shall say, in the first place, that to bring forth is peculiar to the female sex, as to beget is the office of the male: therefore God wills in the first place to render the mind, which is filled with virtue, like to the male sex rather than to the female, thinking it suited to its character to be active, not passive. In the second place both do generate, both the virtuous mind and the wicked one: but they generate in a different manner, and they produce contrary offspring, the virtuous mind producing good and useful things, but the depraved or wicked mind producing base and useless things. In the third place he who is still advancing and making progress is to be incited to the summit itself, and is near to the light which by some persons is said to be delivered to oblivion, and to be made unknown. He therefore, as he is making progress, does not generate bad things, nor yet good things, because he is not yet perfect; but he resembles that man who is neither sick nor yet thoroughly well, but who, after a long sickness, is at last proceeding to convalescence.