זוהר שמות — דף קא ע”א

The Zohar praises the Holy One blessed be He who knows what is in the darkness even when the light is with Him: « He knows what is in the darkness, and the light dwells with Him ». The Zohar treats the mysteries of nocturnal visions, specifying that there are two kinds: those ascending from the side of holiness, and those descending from the side of impurity. Before interpreting a dream, the Zohar introduces a preface on a subject discussed by the Ancients concerning nocturnal visions.