Luke 3:8

(non occ.) For neither does the speed of its sire make the horse swift; but as the goodness of other animals is looked for in individuals, so also that is reckoned to be man's legitimate praise which is decided by the test of his present worth. For it is a disgraceful thing for a man to be adorned with the honours of another, when he has no virtue of his own to commend him.

(non occ.) So then having foretold the casting away of the Jews, He goes on to allude to the calling of the Gentiles, whom He calls stones. Hence it follows, For I say unto you, &c.

But although God can alter and change the most diverse natures, yet in my mind a mystery is of more avail than a miracle. For what else than stones were they who bowed down to stones, like indeed to them who made them. It is prophesied therefore that faith shall be poured into the stony hearts of the Gentiles, and through faith the oracles promise that Abraham shall have sons. But that you may know who are the men compared to stones, he has also compared men to trees, adding, For now the axe is laid to the root of the tree. This change of figure was made, that by means of comparison might be understood to have now commenced a more kindly growth of manhood. Let him then that is able bring forth fruit unto grace, him who ought, unto repentance. The Lord is at hand seeking for His fruit, who shall cherish the fruitful, but rebuke the barren.

(ubi sup.) For it is not sufficient for the penitent to leave off his sins, he must also bring forth the fruits of repentance, as it is in the Psalms, depart from evil and do good, (Ps. 34:14.) just as in order to heal, it will not do to pluck out the arrow only, but we must also apply a salve to the wound. But he says not fruit, but fruits, signifying abundance. (ubi sup.) Not meaning thereby that they had not descended in their natural course from Abraham, but that it avails them nothing to have Abraham for their father, unless they observed the relationship in respect of virtue. For Scripture is accustomed to entitle laws of relationship, such as do not exist by nature, but are derived from virtue or vice. To whichsoever of these two a man conforms himself, he is called its son or brother. (ubi sup.) As if He said, Think not that if you perish the Patriarch will be deprived of sons, for God even from stones can produce men unto him, and prolong the line of his descendants. For so has it been from the beginning, seeing that for men to be made from stones unto Abraham is but equivalent to the coming forth of a son from the dead womb of Sarah.

For what profits the nobleness we inherit through the flesh, unless it be supported by kindred feelings in us? It is folly then to boast of our worthy ancestors, and fall away from their virtues.