Nicene and Post-Nicene Fathers, Vol. V:
On Marriage and Concupiscence.: Chapter 43

Chapter 43.—The Good Tree in the Gospel that Cannot Bring Forth Evil Fruit, Does Not Mean Marriage.

What, then, does he mean by saying, “A tree is known by its fruits,” on the ground of our reading that the Lord spake thus in the Gospel? Was, then, the Lord speaking of this question in these words, and not rather of men’s two wills, the good and the evil, calling one of these the good tree, and the other the corrupt tree, inasmuch as good works spring out of a good will, and evil ones out of an evil will—the converse being impossible, good works out of an evil will, and evil ones out of a good will? If, however, we were to suppose marriage to be the good tree, according to the Gospel simile which he has mentioned, then, of course, we must on the other hand assume fornication to be the corrupt tree. Wherefore, if a human being is said to be the fruit of marriage, in the sense of the good fruit of a good tree, then undoubtedly a human being could never have been born in fornication. “For a corrupt tree bringeth not forth good fruit.”  2286 Once more, if he were to say that not adultery must be supposed to occupy the place of the tree, but rather human nature, of which man is born, then in this way not even marriage can stand for the tree, but only the human nature of which man is born. His simile, therefore, taken from the Gospel avails him nothing in elucidating this question, because marriage is not the cause of the sin which is transmitted in the natural birth, and atoned for in the new birth; but the voluntary transgression of the first man is the cause of original sin. “You repeat,” says he, “your allegation, ‘Just as sin, from whatever source it is derived to infants, is the work of the devil, so man, howsoever he be born, is the work of God.’” Yes, I said this, and most truly too; and if this man were not a Pelagian, but a catholic, he too would have nothing else to avow in the catholic faith.

Footnotes

Matt. vii. 18.