AND THE EARTH WAS VOID AND WITHOUT FORM. This describes the original state-as it were, the dregs of ink clinging to the point of the pen-in which there was no subsistence, until the world was graven with forty-two letters, all of which are the ornamentation of the Holy Name. When they are joined, letters ascend and descend, and form crowns for themselves in all four quarters of the world, so that the world is established through them and they through it. A mould was formed for them like the seal of a ring; when they went in and issued, and the world was created, and when they were joined together in the seal, the world was established. They struck against the great serpent, and penetrated under the chasms of the dust fifteen hundred cubits. Afterwards the great deep arose in darkness, and darkness covered all, until light emerged and cleft the darkness and came forth and shone day came from the side of light, which is the right, and night from the side of darkness, which is the left, and that, having emerged together, they were separated in such a way as to be no longer side by side but face to face, in which guise they clung to one another and formed one, the light being called day and the darkness night, as it says, “And God called the light day and the darkness he called night.” This is the darkness that is attached to night, which has no light of its own, although it comes from the side of the primordial fire which is also called “darkness”. It remains dark until it is illumined from the side of day. Day illumines night, and night will not be light of itself until the time of which it is written, “the night shineth as the day, the darkness is even as the light” (Ps. CXXXIX, 12).
Zohar, Volume 1, Folios 31a and 31b, Soncino translation