Isaac of Acre, Me’irat ‘Einayim, p. 85.

Jewish Mysticism
The Diadem is the revealed world and she is greatly seen by the humble enlightened ones, until in the chamber of chambers they are embarrassed by her more than other people, and rightfully this is the way that it is. Therefore the rabbis, blessed be their memory, instituted the recitation of the supplication prayer, related specifically to her, with closed eyes so that they would not contemplate her. Observe that the rabbis in every matter of modesty of which they speak they mention the Presence because she is revealed greatly and is seen by the one who has received and God, blessed be He, has given him eyes to see. Notice that the rabbis, blessed be their memory, forbade the wearing of the fringe garment, which symbolizes the Diadem, at night.

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