24:35

Allah is the Light of the heavens and earth. The likeness of His light is that of a niche in which is a Lamp. The Lamp is in a glass, the glass, is as it were a glittering star, lighted from a blessed tree, an olive, neither of the east, nor of the west, whose oil would almost grow forth, even if no fire touched it, light upon Light. Allah guides whom He wills to His light, and gave examples to the people; And Allah knows everything.

footnote no. 662 from the Majestic Qur'an:

This is the famous "Verse of Light" about which so much has been said and which Imam al-Ghazali made the object of an entire treatise entitled "The Niche of Lights." Light is that which is itself visible and makes other things visible. "Allah is the Light of the heavens and earth" since Light is that which brings things out of the darkness of non-existence into existence. But Light is also that which brings sentient beings out of the darkness of ignorance and disbelief into the light of faith and knowledge, so that the Qur'an as well as all other divine scriptures can be called light. This is the light of guidance, of His Attribute, the Guide.

"The likeness of His Light" is the light of the Qur'an; "is that of a niche," the niche is illuminated from the inside by the lamp, but is dark on the outside; "in which is a lamp," the lamp is the Qur'an; "the lamp is a glass," the glass is the heart of the believer; "the glass it as it were a glittering stars," the heart of the believer radiates with the light of faith and the Qu'an, which can be seen as the radiance on his face, acts, and speech. This lamp is "lighted from a blessed tree," the tree of revelation, since the tree was always the symbol of the connection between the heaven and earth, hence the tree of al-Hudaybiya under which the Prophet sat to receive the allegiance of his Companions. They each took his hand in turn, the connection between heaven and earth being stated on that occasion explicitly in the Qur'an which says, "the Hand of Allah was above their hands."

The blessed tree is an olive, which in material terms provides an oil that is full of benefits for mankind. "Neither of the east nor the west" since it belongs to the higher world from whence descends revelation, a world beyond the opposition of the pairs. This oil is luminous in itself, but becomes even more so when lighted by the fire of the Qur'an, which is the inward knowledge of Allah and His Attributes and acts. "Light upon Light."

One should take notice of the fact that Allah did not give the sun as an example for the knowledge of the Qur'an, but a lamp which can be extinguished. Nor did He give anything other than fragile glass as an example for the heart of the believer. Glass is easy to break. The precariousness of this situation is here rendered obvious and the fact that such a lamp has to be protected and strengthened is indicated by the next verse, which speaks of how to strengthen it by acts of devotion, detachment from worldly things, and keeping in mind that here shall be a Day of Judgement."