Afterward it is said of Ishmael, and surely no one will doubt that these are words of promise: "He shall be a wild man. His hand shall be against all, and the hand of all against him. He shall dwell over against all his brethren" (Gen. 16:12). To this one may answer that the promise of an angel has less weight than the promise of God. For as a star gives no rays after the sun has risen, so the words of an angel grow dim when compared with God's promise. They disappear and are counted as nothing. Yet this answer only seems to have some force. It is then destroyed by the words of Scripture, which are binding upon us. For it is written: "And Abraham said to God: Let this Ishmael live before Your face" (Gen. 17:18). And God answered him thus: "Behold, Sarah your wife shall bear you a son, and you shall call his name Isaac. I will establish My covenant with him, an everlasting covenant, and with his seed after him. As for Ishmael, behold, I have heard you. Behold, I have blessed him, and will multiply him and increase him greatly. He shall beget twelve nations, and I will make him into a great people. But My covenant I will establish with Isaac, whom Sarah shall bear to you at this time next year" (Gen. 17:19-21). From these words it is evident that by the word of God Himself it is confirmed that Ishmael was born according to promise. Yet this too is resolved as follows. Promise is given properly in the fulfillment of the covenant. It is one thing to bless, multiply, and greatly increase, as is written concerning Ishmael. It is another thing to make someone heir by testament, as is said of Isaac: "I will establish My covenant with him, an everlasting covenant. And with his seed after him." And again in the words that follow: "But My covenant I will establish with Isaac, whom Sarah shall bear to you." Gifts are one thing, and an estate is another. What is determined by law is one thing, and what is received by inheritance is another. For we read that gifts were given to the sons of Abraham's concubines, while the inheritance of all the estate was left to Sarah's son. Therefore, as we have said, even a lawful blessing is one thing, and the covenant is another. Concerning Ishmael one may also say that the word, whether of the Angel or of God, came after his conception. But concerning Isaac, God gave the promise before he was conceived in Sarah's womb. We have said this only insofar as the mediocrity of our natural mind can grasp it. Yet if anyone can devise something greater to explain how Ishmael, born from the maidservant, is not a son of promise, while Isaac, born from the free woman, is such, it is better to hear him. And although, says the Apostle, you have other thoughts, God has revealed even this to you. Now we must rise in brief words to a higher meaning. Each of us is first born not according to promise, so long as he is instructed by the simple words of the Scriptures and still delights in Jewish interpretations. But when he passes to something more exalted and understands the Law as spiritual, then he is born from promise. To speak more plainly, all who constantly do the works of Abraham are born from Abraham. Those who still have the spirit of bondage again unto fear are born from the Egyptian maidservant. Those who have received the spirit of adoption are born from the free woman Sarah. With this freedom we have been endowed by Christ. To the Jews, who even now still desire to be sons of the maidservant, the Lord says: "If you abide in My word, you will truly be My disciples. And you shall know the truth, and the truth shall make you free" (Jn. 8:31-32). Therefore, not knowing that what was said must be understood mystically, they say: "We are Abraham's seed and have never been in bondage to anyone. How then do You say, 'You will be made free'?" Jesus answered them: "Truly, truly, I say to you, everyone who commits sin is a slave of sin. And the slave does not remain in the house forever, but the son remains forever" (Jn. 8:33-35). If we are slaves of sin, then Hagar the Egyptian has given birth to us. But if sin does not reign in our mortal body, then we are truly sons of God.