Allah is the Light of the heavens and the earth.
The parable of His Light is as if there were a Niche
and within is a Lamp: the Lamp enclosed in Glass;
the glass as it were a brilliant star, lit from a blessed Tree,
an Olive, neither of the East nor of the West,
whose Oil is nearly luminous, though fire has hardly touched it.
Light upon Light!
Allah guides whom He will to His Light,
Allah sets forth Parables for men,
and Allah knows all things.
An-Nur 24:35, tr. Helminski
The light which shines in the eye
is really the light of the heart.
The light which fills the heart
is the light of God, which is pure
and separate from the light of intellect and sense.
Mathnawi 1:1126-7, tr. Helminski