Jewish Mysticism
Whoever fixes a thing in his mind with complete firmness, that thing becomes for him the principal thing. Thus, when you pray and recite benedictions, or (otherwise) wish to direct the intention to something in a true manner, then imagine (dimmah) that you are light and all about you is light, from every direction and every side, and in midst of the light a stream of light, and upon it a brilliant light, and opposite it a throne and upon it a good light… Turn to the right and you will find pure light, to the left and you will find an aura which is the radiant light, between them and above the light of glory, and around it the light of life. Above it is the crown of light that crowns the objects of thoughts, illumines the paths of ideas, and brightens the splendor of visions. This illumination is inexhaustible and unending, and out of its perfect glory come grace and blessing, peace and life for those who keep the path of its unity.

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