God is the Light of the heavens and the earth. The parable of His light is that of a niche containing a lamp; the lamp is [enclosed] in glass, the glass [shining] like a radiant star: [a lamp] lit from a blessed tree – an olive-tree that is neither of the east nor of the west the oil whereof [is so bright that it] would well-nigh give light [of itself] even though fire had not touched it: light upon light! God guides unto His light him that wills [to be guided]; and [to this end] God propounds parables unto men, since God [alone] has full knowledge of all things. (Quran 24:35)