Pirqe Rabbi ’Eli‘ezer (Warsaw, 1852), 32, fol. 73b

Jewish Mysticism
R. Simeon said- When Isaac was bound to the altar he lifted his eyes and saw the Presence. But it is written, “man may not see Me and live.” In lieu of death his eyes dimmed when he got older, as it says, “When Isaac was old and his eyes were too dim to see” (Gen. 27-1). From here you learn that blindness is considered as death.

Translated by Elliot Wolfson in Through a Speculum that Shines- Vision and Imagination in Medieval Jewish Mysticism, Princeton- Princeton University Press, 1994.