In the beginning of Parashat Toledot (BeReishit 27:1), we are told that as Yitzchak became older, his eyes aged, and he lost the ability to see. In last week’s Parashah, we are told that Hashem had blessed Yitzchak (25:11). Rashi (ad loc. s.v. VaYehi Acharei Mot Avraham VaYevarech) comments that Avraham was going to bless Yitzchak, but he saw that in the future Eisav would come from Yitzchak and was therefore afraid to give him a Berachah. Therefore, Hashem gave Yitzchak a Berachah instead. However, if Hashem blessed Yitzchak, surely he would have prevented him from suffering this aggravation caused by blindness.
Rashi (27:1 s.v VaTich’henah) presents three possibilities as to how Yitzchak lost his eyesight. The first possibility is that Yitzchak was constantly in the presence of Eisav’s wives who burned incense for their Avodah Zarah, and the constant presence of smoke diminished his eyesight. Alternatively, Yitzchak could have lost his eyesight when angels’ tears fell on his eyes by Akeidat Yitzchak. Rashi’s last explanation is that Yitzchak had to lose his eyesight so that later (27:23) when Ya’akov would approach Yitzchak to steal Eisav’s Berachah, Yitzchak would not be able to recognize who was approaching him and give Ya’akov his brother’s Berachah.
As an aside, if Yitzchak had lost his eyesight from old age, then it would be possible to think that Hashem’s blessings were lacking. However, if Yitzchak lost his eyesight as a result of bad treatment of his eyes, then we would not question Hashem’s Berachah, but rather assume that Yitzchak lost his eyesight as a result of his eye treatment. Therefore, none of the reasons given by Rashi as to why Yitzchak lost his eyesight were that he lost his eyesight in his old age, because that would cause us to think that when Hashem had previously blessed Yitzchak, the Berachah was lacking.
If one of Rashi’s three explanations had been perfect, then Rashi would not have had to come up with two other explanations. Therefore, there must be a fault in each answer which compelled Rashi to give another explanation. The Lubavitcher Rebbe explains the advantages and disadvantages of each of Rashi’s explanations.
The idea that Yitzchak lost his eyesight as a result of smoke damage from Eisav’s wives fits in very well with the previous Pasuk (26:35) which states that Eisav’s wives were a source of strife for Yitzchak and Rivkah. However, if this is the correct approach, then why was Rivkah not blinded by the smoke damage as well? The second explanation, that Yitzchak lost his eyesight when angels’ tears fell on his eyes, answers the question as to why Rivkah was not affected by the smoke damage. However, this answer is Midrashic and is a non-literal reading of the Pasuk. This compels Rashi to give the more literal explanation that Hashem actually took away Yitzchak’s eyesight. This answer fits in with the Pasuk, because we are told that Yitzchak lost his eyesight at an old age (27:1), which fits in with the idea that he lost his eyesight right before Ya’akov came to Yitzchak to receive his Berachah. According to Rashi’s first two answers, it seems that Yitzchak lost his eyesight at a younger age, and this does not fit in with the literal reading of the text. Therefore, Rashi’s third answer is the strongest.
However, according to Rashi’s third explanation, why did Hashem have to take away Yitzchak’s eyesight and make him suffer in order for Ya’akov to receive the Berachah? Why didn’t Hashem just tell Yitzchak to give Ya’akov the Berachah?
With this last approach, Rashi is teaching us the lengths that Hashem went to in order to avoid speaking Lashon HaRa about Eisav. Rather than telling Yitzchak directly to bless Ya’akov in place of Eisav, who would become a Rasha, Hashem decided to blind Yitzchak. Like Hashem, we must take great measures to ensure proper treatment of others.