Jewish Mysticism
It has been taught- when God revealed himself on Mount Sinai all of Israel saw as one who sees from a light in a crystal. From that light each one saw that which Ezekiel the prophet did not see. Why? For those upper voices were revealed [or, according to a variant reading, inscribed] in one, as it is written, “And all the people saw the voices.” By Ezekiel, however, the Presence was revealed in her chariot and no more. Ezekiel saw as one who sees from behind many walls.

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