And Rebekah spoke unto Jacob, her son, saying: “Behold, I heard thy father speak unto Esau thy brother, saying: Bring me venison, and make me savoury food, that I may eat, and bless thee before the Eternal before my death. Now, therefore, my son, hearken to my voice according to that which I command thee. Go now to the flock, and fetch me from thence two good kids of the goats; and I will make them savoury food for thy father, such as he loveth; and thou shalt bring it to thy father, that he may eat, so that he may bless thee before his death.” And Jacob said to Rebekah his mother: “Behold, Esau my brother is a hairy man, and I am a smooth man. My father peradventure will feel me, and I shall seem to him as a mocker; and I shall bring a curse upon me, and not a blessing.” (Genesis 27:6-12)
This Torah portion presents many difficult questions. According to tradition, our patriarchs and matriarchs were the most righteous of people. What are we to make of Rebecca’s conspiring with Jacob to deceive her husband—Jacob’s father—Isaac in order to steal the blessing intended for her other son, Esau? Moreover, according to the Kabbalah, Jacob was the embodiment and personification of the sefirah of Tiferet, which signifies beauty, mercy, harmony, and truth. We might have expected a man who personifies the category of truth to recoil from his mother’s proposal to deceive his father. However, he raises no moral objections to her suggestion. Jacob’s only objection is that he may get caught in the act and get the opposite of a blessing. At first blush, this appears to be the position not of a conscientious objector but of a coward. How are we to understand this very troubling account?
The questions do not stop here. When Jacob comes to his father, Isaac, impersonating Esau, the Torah records the following dialogue:
And he came unto his father, and said: “My father”; and he said: “Here am I; who art thou, my son?” And Jacob said unto his father: “I am Esau thy first-born; I have done according as thou have spoken to me. Arise, I pray thee, sit and eat of my venison, that thy soul may bless me.” (Genesis 27:18–19)
Commenting on this account of Jacob’s apparent deception, Rashi states, “I am…Esau…your firstborn: [He meant]: I am the one who is bringing you [food], and Esau is your firstborn.” Rashi is the foremost classical commentator. Is Rashi trying to justify Jacob’s lie by saying that, technically, Jacob did not lie? According to Rashi, first Jacob said, “I am,” meaning “I am the one who brings you the food;” and then Jacob added, “Esau is thy first-born”—both are factually accurate statements. This sounds very Clintonesque.
An additional puzzle comes as the hoax is uncovered. Here is the dialogue between Esau and his father, Isaac:
And Isaac trembled very exceedingly, and said: “Who then is he that hath taken venison, and brought it me, and I have eaten of all before thou camest, and have blessed him? Yea, and he shall be blessed.” (Genesis 27:33)
Upon realizing that Jacob tricked him by impersonating Esau, why didn’t Isaac revoke his blessing? Why did he instead reaffirm it—“Yea, and he shall be blessed”?
Many a commentator has struggled with these questions. Interested readers are directed to read classical Torah commentaries for various proposed explanations. Here is how this troubling narrative can be read through the prism of quantum physics:
As I discussed in my earlier essay “The Entangled Twins,” Jacob and Esau were “entangled” as twin brothers. Just as two entangled particles in quantum mechanics represent a single system described by a single wave function, twin brothers are also a single system called “twins.” As also discussed in “The Entangled Twins,” they share a symmetry, such that the brothers are “interchangeable”—if we were to swap them, the sum total would be the same. As mentioned, this symmetry allows Jacob to present himself instead of his brother, Esau.
But let us start with Rebecca—the mastermind of this intrigue. When pregnant, Rebecca received a prophecy:
And the Eternal said unto her: Two nations are in thy womb, and two peoples shall be separated from thy bowels; and the one people shall be stronger than the other people; and the elder shall serve the younger. (Genesis 25:23)
Rebecca feared that Isaac, unaware of this prophecy, would put Esau above Jacob (as, indeed, Isaac intended to do when he put Jacob the lord over his brother, thinking that he was blessing Esau). She knew that Esau, a wild man who spent his days hunting animals and chasing women, was not suited for such a leadership role. Esau had great potential, which Isaac saw and wanted to harness. However, Rebecca knew from the prophecy she received that this potential would not be realized until the end of days. She knew that it was Esau who was destined to serve Jacob.
Rebecca felt justified in masterminding the ruse as carrying out G‑d’s will, to which she was privy, but her husband was not. From her perspective, she was not encouraging Jacob to steal his father’s blessing; she was merely steering Isaac’s blessing in the right direction. Moreover, intuitively sensing that two brothers were “entangled,” she did not see anything wrong with substituting one twin brother for another, knowing that, as an entangled pair, they would both get the father’s blessing. However, the one receiving the blessing would be put ahead of the other—which was her objective in carrying out G‑d’s will.
Jacob did not object to this ruse on moral grounds for the same reason—he was happy to receive his father’s blessings on behalf of himself and his brother. His mother may have told him of his destiny as the future head of the family, which may be why Jacob bought the birthright from his older brother.
What was Jacob’s fear? He knew his father was blind. He expected that when he brought food to his father, Isaac would see a son but know not which son (which was indeed what happened). Thus, in the blurry vision of Isaac, that unidentified son would be, as it were, in a superposition of two “states”—Esau and Jacob. Jacob feared that, if his father touched him and thus recognized him, his father would “collapse the wave function” (which occurs whenever any measurement or observation is made), collapsing the state of superposition into a single state. Isaac would realize that it was Jacob who stood in front of him. And that, Jacob feared, might elicit the opposite of a blessing.
We can also understand in the same vein Jacob’s answer to his father’s query, “Who art thou, my son?” And Jacob said unto his father: “I am Esau thy first-born.” As Rashi explains, Jacob makes two statements here: one—“I am” and the second—“Esau thy first-born.” Because Jacob views himself as a part of the whole—the entangled twins—he tells his father that he was there not only on his behalf (“I am”) but also on behalf of his brother (“Esau thy first-born”).
However, as Jacob expected, Isaac wanted to touch him. Rebecca’s trick of covering Jacob’s hand with goat skins worked, and Isaac did not recognize Jacob. But Isaac intuitively sensed the presence of both sons in the room, as he said:
The voice is the voice of Jacob, but the hands are the hands of Esau. (Genesis 27:22)
Thus, Isaac acknowledged the “entanglement” of the twin brothers. As Rebecca expected, Isaac put the son in front of him above his brother. However, instead of Esau, it was now Jacob who was put in the leadership position.
We can now also understand the dialogue between Isaac and Esau, when Isaac realizes the ruse but reaffirms his blessing to Jacob all the same: “Yea, and he shall be blessed.” Isaac may have intuitively realized that, by touching Jacob, he had “collapsed” the wave function (as Jacob expected), as it were. There was no going back. Once he appointed Jacob as the head of the family, it could not be undone—one cannot un-collapse the wave function.
As we see, the logic of quantum mechanics sheds new light on this biblical narrative, not only explaining difficult verses, but also Rashi’s commentary.
Does this mean that Isaac, Rebecca, and Jacob knew about the superposition of states, entanglement, or the collapse of the wave function? Of course not. These terms were not in their vocabulary, and the formalism of quantum mechanics would not be developed for more than three thousand years. Besides, we use these terms metaphorically in any event. However, it may mean that they intuitively followed the Torah’s inner logic, which is compatible and structurally parallel with the logic of quantum mechanics.
 Rashi, of course, is not stating his own opinion—he is quoting the explanation offered by Midrash Tanhuma. Generally, such moral equivocation, falls under the rubric of “mental reservation”—an ethical doctrine in moral theology and ethics that recognizes the “lie of necessity.” A 14th century biblical commentator Rabbi Aharon ibn Alrabi, links this Rashi explicitly to this doctrine, although he goes on to reject it as a satisfactory justification of Jacob’s act. Well-known biblical examples of the mental reservation include Abraham’s introduction of his wife Sarah (or Sarai) as his “sister” in Egypt (Genesis 12:11–13) and later to Abimelech (Genesis 20:12)—Sarah was indeed his half-sister (or a niece). Similarly, Isaac introduced his wife, Rebecca, as his sister to Abimelech as well (Genesis 26:7)—Rebecca was indeed his cousin (which in some languages is called “sister”). Mentalis restrictio presented particular challenges to Christian theologians for whom a lie was deemed intrinsically evil and never allowed. However, under certain circumstances, telling a lie is the only way to overt harm or to keep one’s duty. The validity of such equivocations was admitted by all moral theologians. In Judaism, this is less of a problem, because Rabbis see an example of G‑d Himself telling an untruth to avoid embarrassing Abraham when He asked, “Wherefore did Sarah laugh, saying: Shall I of a surety bear a child, who am old?”, when, in fact, she said that “my lord (that is, Abraham) being old also (Genesis 18:12–13). Rashi (based on Genesis Rabbah 48:18) learn from this episode that, sometimes, to avoid embarrassing a person or to avoid creating a domestic conflict between husband and wife, a lie can be meritorious. (See also Yevamot 65b; Vayikra Rabba 9:9.) Jacob’s answer to his father would be classified as a “wide mental reservation,” in which case the equivocation comes from the ambiguity of the words themselves. The Maharal points out a textual basis for the Rashi’s interpretation, in that Jacob says anochi (a rare form of “I”) rather than the ordinary ani (colloquial “I,” which Eisav, in fact, later uses when he identifies himself), based on Hebrew grammar. I would like to propose a different explanation also based on the use of the unusual anochi instead of the usual ani. The word anochi is spelled alef-nun-chof-yud. If we switch the last two letters—alef-nun-yud-chof—it spells the words ani k’. Ani stands for the usual “I,” and the prefix “k,” called in Hebrew grammar, chof hadimiyan, is a prefix signifying an approximate equivalence and usually translated as “something like…” Thus, by saying anochi, Jacob hinted to Isaac that he was not really his firstborn Esau, but only “something like” Esau—ani k’Eisav—in other words, Esau’s impersonator. This allowed Jacob to obey his mother’s order while being truthful with his father. This is a vivid example of “wide mental reservation.”
 In this context, we use the quantum-mechanical term, “entangled,” metaphorically. However, it is possible to construct a conceptual Hilbert space where twin brothers would be described by a single wave function and, therefore, entangled in the literal sense.