The Torah portion Vayeitzei begins by relating how G‑d revealed Himself to Ya’akov while he was traveling to Charan. G‑d begins his address by saying:1 “I am G‑d, L-rd of Avraham your father, and L-rd of Yitzchak.”

The Midrash notes2 that, although G‑d generally does not affiliate His name with tzaddikim — “L-rd of Avraham,” “L-rd of Yitzchak,” etc. — while they are still alive (for it is possible that they may yet sin), He made an exception in the case of Yitzchak, calling Himself “L-rd of Yitzchak,” even though Yitzchak was still alive.

The Midrash explains that “since he [Yitzchak] was sightless, it was considered as if he had already passed on; for he was confined to his home, and the evil inclination had ceased its blandishments.” G‑d was thus assured that Yitzchak would not sin in the future, and could confidently affiliate His name with him.

Although it is true that G‑d knows the future, and whether a tzaddik will or will not eventually succumb to sin,3 He refrains from explicitly stating His affiliation with tzaddikim while they are alive, for when G‑d’s knowledge is clearly revealed, it inhibits man’s free will.4

But since Yitzchak’s evil inclination had ceased to tempt him, there was no possibility that, by declaring Himself “L-rd of Yitzchak,” G‑d would nullify his freedom of choice.

But this must be better understood. It is quite true that a sightless person is considered as if he had died, as our Sages state:5 “Four categories of people are considered as if they were dead: an impoverished person, a leper, a sightless individual and he who has no children.” There is even an opinion6 that a blind person — like a dead one7 — is free from the obligation of performing mitzvos.

Nevertheless, this does not appear to be reason enough for the Midrash to state that because Yitzchak was blind, the evil inclination held absolutely no sway. We can observe that a sightless person possesses an evil inclination, harbors forbidden desires, and is quite capable of sinning. How then does the Midrash state that G‑d affiliated His name with Yitzchak while he was still alive because “he was sightless … and the evil inclination had ceased its blandishments”?

According to our Sages,8 Yitzchak became blind because of the smoke from the incense and other offerings that Esav’s wives offered to their idols. Now, although it is true that smoke is damaging to the eyes,9 we must recognize the fact that this smoke was not so dense that it caused everyone who came into contact with it to be blinded, for if this were so, then Esav’s wives, as well as Esav himself, should also have been blinded. Why then did this smoke blind only Yitzchak?

In fact, Yitzchak’s blindness did not result from the smoke itself, but because the smoke was a byproduct of idolatry. Yitzchak, who was “pure of eye, incapable of seeing evil,”10 was so repulsed by this smoke that it caused him to become sightless.

This is similar to an incident involving R. Nochum of Chernobyl, who was once inadvertently given non-Jewish milk and was simply unable to see it. In explaining this phenomenon, R. Nochum noted: “That which a Jew should not see, he does not see.”11

Since Yitzchak’s blindness resulted from his utter inability to tolerate anything idolatrous, “the evil inclination ceased its blandishments.” Evil now held absolutely no sway over him.

Because Yitzchak had attained such an exalted state, it was possible for G‑d to affiliate His name with him even while he was still alive.

Based on Likkutei Sichos, Vol. V, pp. 132-140