It is written, "Abram's wife Sarai bore him no children." (Gen. 16:1); that is, she was barren. Instead, she gave her servant Hagar, an Egyptian and the daughter of Pharaoh, to Abram as a concubine:
"And Sarai, Abram's wife, took Hagar the Egyptian, her handmaid....and gave her to Abram her husband to be his wife. And he went in unto Hagar, and she conceived." (Italics mine, Gen. 16:3-4)
Notice the phrase, "....and he went in unto Hagar," which literally means he had sexual intercourse with her. For example, Rashi states:
"AND HE WENT IN UNTO HAGAR: This means she conceived from the first [sexual] intercourse." (Commentaries Genesis 16:3-4)
From this physical union, Ishmael was born -- and born prior to the Brit Milah, when Avraham was still uncircumcised and therefore bore the name "Avram," which lacked the Hebrew letter Heh, denoting the Holy Spirit. By contrast, however, consider the conception and birth of Avraham's "second" (but actually first-born) son, Isaac.
Whereas Ishmael was born before God's covenant of circumcision with Avram -- as a result of which he was elevated to the status of Avraham by the implanting of the Holy Spirit -- Isaac came after. That is, Abram was uncircumcised and, therefore, empty of the Holy Spirit, when he entered Hagar; he was not yet Abraham, in whom God would later plant the Holy Spirit and to whom He would then give the birthright and the promises, as He did prior to the birth of Isaac.
This means that Ishmael was the product of the union between an uncircumcised Gentile (i.e., Avram) and Pharaoh's daughter, since the Midrash identifies Hagar as such. For example, the first century, Pirke de Rabbi Eliezer, states, "We know that Hagar was the daughter of Pharaoh" (26:31A.ii), and the Zohar says:
"Observe how the great love of the Almighty towards Abraham was manifested in the fact that Isaac was not born to him until he was circumcised. In this way it was made certain that his seed would be holy [italics mine]....For had Abraham begotten before he was circumcised [as he did with Ishmael], his seed would not have been holy, as it would have issued from the state of unholiness and thus would have clung to that state here below. But after Avraham's circumcision the seed issued from the state of holiness and became attached to supernal holiness, and he begat [Isaac] in the higher plane." (Italics mine, Zohar 1:103b)
It was for this reason that God withholds His Covenant from Ishmael, but gives it instead of Isaac -- the former was "begotten before [Abraham] was circumcised," while the latter came afterward. Thus, the Zohar can say that only Isaac "issued from the state of holiness" and, even more significantly, was begotten "on a higher plane." In other words, Ishmael's conception was before his father's circumcision, and consequently he was the offspring of a sexual union between a natural man (Avram) and an equally natural woman (Hagar). But Isaac's paternity, on the other hand, was supernatural, on a "higher plane," and took place between a man and a woman (Avraham and Sarah) in whom the Holy Spirit had been implanted, thus raising them to kinship with God in a way that had not been present at the conception of Ishmael between the un-Spirited Avram and Hagar. As Jung points out:
"The [implanting] of the Holy [Spirit], the third Divine Person, in man, brings about a Christification of many." (C. G. Jung, Answer to Job, par. 758)
Thus, Isaac's paternity was supernatural while that of Ishmael was natural, in that "the seed from which [he] came issued from the state of Holiness and became attached to Supernal holiness." This situation is taken one step further in the passage:
"The Lord God remembered Sarah as he had said....and did what he had promised her. And so, Sarah conceived and bore a son to Abraham. (Gen. 21:1-2)
Even more importantly, note that according to Genesis, Abraham himself did not "go in unto Sarah" (i.e., have sexual intercourse with her) as he had with Hagar; it does not say in Scripture, ".....and Abraham went in unto Sarah and she conceived," but instead reads, "the Lord God did [unto her] what He had promised....And so Sarah conceived." In other words, Isaac was born of what might be called "Miraculous Conception" while Ishmael was not. This is confirmed in the Oral Torah which unequivocally states:
"The child [Isaac] was conceived in a miraculous manner." (The Midrash Says, vol. 1, p. 149)
Furthermore, even Rashi brings down that "remembered" -- in the passage, "and the Lord God remembered Sarah....and did what he had promised her" -- literally means conception and the word "promised" means birth. (Rashi's Commentaries, Genesis 21:1-2) This same theme, and what it strongly implies, is also taken up in the Zohar:
"Besides 'visiting' Sarah, God also 'did' something in the region on high. [Italics mine] Hence, the two stages of first 'visiting' and then 'doing,' combined with the Name of God, mentioned in each; the whole forming one process." (Zohar 1:115a)
Yet another passage from Rashi suggests this "Miraculous Conception" of Isaac, but not Ishmael:
"[God] made a scratch for [Abraham] on the wall; He [then] said, 'When the sun reaches this scratch [I will return to Sarah], and in the following year, she will give birth.' " (Ibid)
Thus, on all possible levels, the conception of Isaac was miraculous, while that of Ishmael was mundane. For this reason, God later identifies Isaac, and not Ishmael, as Abraham's only son, heir to the Birthright and Promises He has given to Abraham, when He states:
"Take your son, your only child, Isaac.....etc." (Gen. 22:2)
because Isaac -- and, by extension, Israel who springs from him -- carries the Holy Seed and is therefore the only heir to the Covenant, while Ishmael is not. As God stated in Scripture:
"I will make [Ishmael] a great nation. But my covenant will I establish with Isaac." (Gen. 17:21)
And it was through Jacob, the son of Isaac, that Israel came into being (and the Jews with him) in order to be a "light unto the Gentiles" and the divine Instrument of Judgment by whom "all the families of the earth be blessed." (Gen. 12:2-3) We will consider this mystery of the Patriarch Jacob, who was elevated to the status of Yisrael ("A Prince of God"), in what follows.