By Rabbi Joshua (optically known as The Hoffer) Hoffman z"l
Yosef learns that his father Yaakov is sick, and goes to see him. He takes his two sons, Menashe and Ephraim, along with him, hoping that his father will bless them before he dies. The Torah then tells us that Yisroel (Yaakov )saw the sons and asked who they are( Bereishis, 48:8). Yosef tells him that they are his children, and Yaakov tells him to bring them close to him so that he can bless him. The Torah then says something very strange, in light of what we have seen so far " The eyes of Yisroel were heavy with age, he could not see, so he brought them near him and he kissed them and hugged them" (Bereishis, 48:10). Two verses previously, we were told that Yisroel saw. Yosef's children, and now we are told that he could not see them! Moreover, Yaakov didin't seem to have any problem in recognizing Yosef.The classical commentators, of course, noticed this seeming discrepancy, and attempted to explain it. The Chizkuni says that when the Torah says that Yaakov saw the children, it was in the category of 'seeing and not seeing,' meaning that he did not see them clearly. His recognition of Yosef, says the Chizkuni further, was through his voice rather than through his appearance. The Rashbam says that Yaakov saw the the human forms of the children, but did not recognize their faces. Among more recent commentators, we find that the Netziv explains that that Yaakov needed to forge deep connection with Ephraim and Menashe so that he would get the divine inspiration and help he would need to give them a blessing. That is why he kissed them and hugged them.
Rashi addresses a different question. What did Yaakov mean to ask when Yosef brought his sons to see Yaakov, and Yaakov asked, who are they? Hadn't Yaakov already met Yosef's two sons during his seventeen years in Egypt? The midrash, cited by Rashi, explains that Yaakov saw Yerovom and tachav coming from these children, and wondered how such evil people could be worthy of a blessing. Rav Yisroel of Gur, in his Beis Yisroel, says that in light of this midrash, we can understand the verses that follow. He says that when the Torah tells us that Yaakov's eyes were heavy from old age, the word for old age, 'ziknah,' also refers to Yaakov's honored status, or, more specifically, to the fact that he was a tzaddik, a righteous person, and righteous people do not see evil.In this instance, it was through Yosef's prayer, after sensing that Yaakov saw something wrong in Ephraim and Menashe, that Yaakov did not fully discern who these descendants would be and what they would do.This was actually a character trait of Yosef, who, as te Talmud tells us, was not subject to the 'ayin hora,' or bad vision, meaning, people looking at him in a psychologically dangerous way. Yosef rose above ayin hora because he himself did not look for bad in people. He prayed that Yaakov, too, would be given this special vision so that his prophetic powers would not see those evil descendants who would come from his grandchildren.
Interestingly, the compendium Tallelei Oros cites another explaantion ofYaakov's inability to see due to 'ziknah' from the great medieval Talmudic commentator and halachic authority, the Ritva. The Ritva explains that ziknah here refers to Torah wisdom. The exertion that Yaakov put into his Torah learning, says the Ritva, caused his eyes to begin to fail. This is similar to what the Rambam says, in his commentary to the Mishneh, in explanation of Rabbi Eliezer ben azariah's statement, when he was eighteen , that he is like a seventy-year old man. The Rambam says that Rabbi Eliezer's hair turned prematurely white as a result of the long hours that he put into his Torah study. Seen in this way, perhaps we can suggest that Yaakov did not see bad in people, as the Beis Yisroel says, but not because Yosef prayed for this to be so, but because he studied Torah which such diligence. As the Sefas Emes points out, Yaakov had the trait of 'emes,' of truth, and this comes from intense involvement in Torah study, through which one becomes able to see the truth. In this way, he was able to see the inner essence of people, and realize that they are basically good.
The Sefas Emes further says that it was Yaakov's trait if emes that carried the Jewish nation through their exile, and this is the message of the juxtaposition of the end of Vayigash, which speaks of the Jewish people taking hold in Egypt, and the beginning of Vayechi, which tells us that Yaakov lived in Egypt for seventeen years. Through involvement in Torah study, Yaakov was able, in the seventeen years that he lived in Egypt, to prepare his people for the exile experience. In parshas Vayigash
(Bereishis, 46:48), we are told that on the way down to Egypt , Yaakov sent Yehudah ahead to instruct them towarsd Goshen. The simple meaning of this verse is that Yaakov sent Yehudah ahead to give proper directions. However, Rashi cites a midrash which says that Yaakov sent Yehudah ahead in order to set up a house of Torah study, so that 'to instruct' means, to instruct in Torah. This is also how Onkeles translates the verse. By seeing to it that there would be a place for Torah study in Egypt, Yaakov was assuring that the Jewish people would survive exile spiritually intact, by learning how to look at the world through the eyes of Torah.