Bede

But for Adam there was not found a helper like him. Therefore, the Lord God cast a deep sleep upon Adam; and while he was sleeping, he took one of his ribs and filled up flesh for it. And the Lord God built the rib which he had taken from Adam into a woman. Since the woman was made from the man's side, it is to be believed that this happened to commend the power of that conjunction. But that it was done to him while he was sleeping, with the bone removed and flesh filling its place, was done for the sake of a higher mystery. …

Commentary on Genesis (Hexaemeron) ↗