Allah is the light of the heavens and the earth; a likeness of His light is as a niche in which is a lamp, the lamp is in a glass, (and) the glass is as it were a brightly shining star, lit from a blessed olive-tree, neither eastern nor western, the oil whereof almost gives light though fire touch it not-- light upon light-- Allah guides to His light whom He pleases, and Allah sets forth parables for men, and Allah is Cognizant of all things.