Yitzchok is getting old and wants to bless his children. He becomes blind.

One of the reasons given is so that he should not be able to see, enabling him to bless Yakov rather than Esav.

The question arises as to why Hashem didn’t just inform Yitzchok that Esav was a bad person, why make him blind for 57 years? The answer is, that although Yakov had an idea who Esav was, Hashem did not want to speak badly about another Jew. לקו״ש טו