118. "And it came to pass, that when Isaac was old" (Beresheet 27:1). Rabbi Shimon said, It is written, "And Elohim called the light Day, and the darkness he called Night" (Beresheet 1:5). This verse had already been explained; nevertheless come and behold, All the actions that the Holy One, blessed be He, performs, are true, and in the secret of the upper world. And all the words of the Torah are words of faith, WHICH IS THE SECRET OF THE NUKVA, and supernal mysteries, WHICH ILLUMINATE IT as they should.
119. Come and behold, Isaac did not have the merit of Abraham, whose eyes were not blinded or dimmed. Here, however, is a supernal secret, the secret of faith. For we have learned that "And Elohim called the light Day" refers to Abraham, the light of day, THE SECRET OF THE RIGHT COLUMN, whose light grows stronger as the day advances, THE SECRET OF THE LIGHT OF CHASSADIM.
120. Thus, it is written, "And Abraham was old, advanced in age" (Beresheet 24:1), that is, in the shining lights OF CHASSADIM. And he is old, as it is written, "that shines ever more brightly until the height of noonday" (Mishlei 4:18). Therefore IT IS WRITTEN OF HIM, "And Elohim called the light Day." "And the darkness he called Night." This is Isaac, who is dark, and gets DARKER to receive the night within him. Therefore, when he grew older, it is written, "And it came to pass, that when Isaac was old, and his eyes were dim, so that he could not see" (Beresheet 27:1). FOR HE BECAME COMPLETELY DARK. Assuredly he had to be COMPLETELY dark, to cleave well to his grade.
121. Rabbi Elazar, his son, kissed his hands and said, This is well. Abraham shines on the side of his grade, and Isaac is darkened on the side of his grade. But why did Jacob GROW DARKER, as it is written, "Now the eyes of Yisrael were dim (lit. 'heavy') from age" (Beresheet 48:10). He answers, Assuredly it is AS I SAID, for it is written, "heavy," and not dim, AS WAS WRITTEN OF ISAAC; It is written "from age", not 'his age.' "From age" is to be interpreted as the age of Isaac, FOR HE INCLUDED BOTH ABRAHAM AND ISAAC. THEREFORE on the side OF ISAAC his eyes "were heavy...so that he could not see" (Ibid.), not properly, but he was not absolutely blind. But Yitzchak's eyes were completely dim, and it became darkness, for night, WHICH IS THE NUKVA, clove to him and it was fulfilled, "and the darkness he called Night."