14 And how are they born? Because they become sons of God and brethren of Christ, they are certainly born. For if they are not born, how can they be sons? But the sons of men are born of flesh and blood, and of the will of man, and of the embrace of wedlock. But in what manner are they born? “Who not of bloods,” as if of male and female. Bloods is not Latin; but because it is plural in Greek, the interpreter preferred so to express it, and to speak bad Latin according to the grammarian that he might make the matter plain to the understanding of the weak among his hearers.
For if he had said blood in the singular number, he would not have explained what he desired; for men are born of the bloods of male and female. Let us say so, then, and not fear the ferule of grammarians, so long as we reach the solid and certain truth. He who understands it and blames it, is thankless for his having understood. “Not of bloods, nor of the will of the flesh, nor of the will of man.” The apostle puts flesh for woman; because, when she was made of his rib, Adam said, “This is now bone of my bone, and flesh of my flesh.” And the apostle says, “He that loves his wife loves himself; for no one ever hated his own flesh.” Flesh, then, is put for woman, in the same manner that spirit is sometimes put for husband.
Wherefore? Because the one rules, the other is ruled; the one ought to command, the other to serve. For where the flesh commands and the spirit serves, the house is turned the wrong way. What can be worse than a house where the woman has the mastery over the man? But that house is rightly ordered where the man commands and the woman obeys. In like manner that man is rightly ordered where the spirit commands and the flesh serves.
Source: Tractates on the Gospel of John (New Advent)