Gen 25:21

“First of all consider why it is that many holy women in the Scriptures are related to have been barren, as Sarah herself, and now Rebekah. But also Rachel, Israel's beloved, was barren. Hanna also, the mother of Samuel, is recorded to have been barren. But also in the Gospels Elizabeth is related to have been barren. Yet in all these instances this term is used because after sterility they all gave birth to a holy person.”

“And Rebecca conceived, and by her patience she untied the knot of sterility. But let us consider what the prophetic and apostolic soul gives birth to and how it gives birth. She went, it says, to inquire of the Lord (Gen. XXV, 22), because the infants in her womb were rejoicing. And she received this answer: Two nations are in your womb (Ibid., 23); for she presumes nothing of her own accord, but in all things she seeks the highest God as the ruler of her plans. In fullness of peace and piety, she joins together two peoples by her faith and preaching, and she encloses them as in her own womb. She is rightly called sister more than wife, because she adopts the name of a gentle and peaceful soul of shared piety rather than a special bond; and because she considers herself more bound to all than to one.”

“One question is worth raising initially: If she and her husband were conspicuous for their good life and both concerned for chaste living, why was she barren? We cannot find fault with their life or say barrenness was the result of sin. To grasp the full extent of this remarkable circumstance, remember that it was not only herself who was barren but also the good man's mother, Sarah; and not only his mother but also his daughter-in-law—I mean Jacob's wife Rachel.What is the meaning of this gallery of sterile people? All were good people, all virtuous, all given testimony by God; of them he said, "I am the God of Abraham, the God of Isaac and the God of Jacob." And blessed Paul says, "Hence God is not ashamed to be called their God." There is great commendation of them in the New Testament; great praise of them in the Old. In each case they were distinguished and remarkable men, yet all had barren wives. They spent a long period in a childless condition. So whenever you see a man and wife of virtuous life experiencing childlessness, whenever you see pious people devoted to religion yet childless, don't think it is the result of sin. After all, many reasons for God's designs are beyond our understanding, and we ought to thank God for everything and brand as wicked only those living in sin, not those without children. It frequently happens, in fact, that God works things for our good without our realizing the reason for what happens. Hence in every case we should marvel at his wisdom and praise his ineffable love.”

“These things are told for our benefit so that we may give evidence of much goodwill and not pry into God's plans. Yet we need to explain the reason why these women were barren. What, then, is the reason? So that when you see the Virgin giving birth to our common Lord you may not be incredulous. Exercise your mind, it is saying, on the womb of these sterile women, so that when you see an infertile and sealed womb opened for childbearing by God's grace, you may not be surprised to hear that a maiden gave birth. Or rather, feel surprise and amazement but don't refuse faith in the marvel. So when the Jew says, "How did the Virgin give birth?" say to him, "How did the sterile old woman give birth?" In that case, you see, there were two impediments, her advanced age and the imperfect condition of nature, whereas with the Virgin there was one impediment, her not having experienced marriage. Consequently the barren woman prepares the way for the virgin.”

“(Verse 21.) And Rebecca his wife conceived, and the sons within her were moved. Concerning this movement, the Seventy Interpreters rendered it as ἐσκίρτων, which means they were playing or kicking; which Aquila translated as they were breaking in the womb. But Symmachus rendered it as διέπλεον, which means they were carried on the surface like a ship.”

“Thus Isaac, the son of the promise, who as a figure of our Redeemer became obedient to his father even unto death, was born of parents who were old. He had a mother who had long been barren. Thus Jacob, the patriarch Joseph, Samson, [who was] the bravest of the chieftains, and Samuel, [who was] the most distinguished of the prophets, [all] had as their progenitors [mothers who were] for a long time barren in body but always fruitful in virtues. In this way their dignity would be known from the miraculous nativity of those who were born, and it might be proven that they would be famous in their lives, since at the very outset of their lives they transcended the norms of the human condition.”

“וַיֶּעְתַּר AND ISAAC ENTREATED —He prayed much and urgently. וַיֵּעָתֶר לו WAS ENTREATED OF HIM — He let himself be urged, conciliated and influenced by him. I say that wherever this root עתר occurs it has the meaning of heaping up and increasing. E. g., (Ezekiel 8:11) “And a thick (עתר) cloud of incense” which means an abundance of ascending smoke; (Ezekiel 35:13) “You have multiplied (העתרתם) your words against me”; (Proverbs 27:6) “The kisses of an enemy are importunate (נעתרות)”—they appear to be too many and therefore they are burdensome. old French encresser; English to increase. לנכח אשתו FACING HIS WIFE — He stood in one corner and prayed whilst she stood in the other corner and prayed (Genesis Rabbah 63:5). ויעתר לו [AND THE LORD] WAS ENTREATED OF HIM — of him and not of her, because there is no comparison between the prayer of a righteous person who is the son of a righteous person and the prayer of a righteous person the child of a wicked-person — therefore God allowed himself to be entreated of him and not of her (Yevamot 64a).”