The Prophet tells us that God created angels out of light. Light is a name of God, and the Koran tells us that "God is the light of the heavens and the earth" (24:35). In order to understand what angels are, we have to understand what light is. It will not help us much to think about light in physical terms. Rather, we have to grasp the signs that are revealed to us when we observe light. 

Normally, we think of light as visible, but in fact, it is invisible. We can only see light when it is mixed with darkness. If there were only light and no darkness, we would be blinded by its intensity. Look at what happens when you gaze at the sun, which is 93 million miles away and is viewed through the earth's atmosphere. If we moved outside the atmosphere, just few miles closer to the sun, we could not possibly look at it for a moment without losing our eyesight. What we call visible light is pretty pale stuff. It can hardly compare with unfiltered sunlight, much less with the divine light, which illuminates the whole cosmos. Hence, it is said in Islam that God's light is so bright that people have all been blinded by it. 

God is unseen, angels are unseen, and light is unseen. Thus it should not be surprising that God and angels are light. You might object and say that we see light shining everywhere, but we don't see angels or God. Don't we? Tawhid (Unity of God) is telling us that the signs are nothing but God's radiance, and the creatures are nothing but the outward marks of God's creative power. "God is the light of the heavens and the earth" (24:35), and the heavens and the earth are the radiance or the reflection of that light. 

Light is invisible, but without light we see nothing. Hence, light can be defined as an invisible something that makes other things visible. So also, God and the angels are invisible, but without them there would be no universe. Hence, God and the angels can be described as invisible somethings that make the universe visible. 

The opposite of light is darkness, and darkness is simply the absence of light. In other words, light is something, but darkness is nothing. We see things because a nothing has mixed with a something. We would not be able to see if there were only light, or if there were only darkness. Light and darkness must come together for vision to occur. 

God is Light. The opposite of light is darkness, which is nothing. In other words, God has no real, existing opposite, since nothing is not really something. If nothing is there, how can we talk about opposites? Of course, we say that nothing is the opposite of something, but this nothing does not exist except as a figure of speech or as an object of supposition for the purpose of discussion and explication. 

Are creatures' light or darkness? The answer, of course, is that they are neither, or that they are both. If they were light and nothing but light, they would be God, and if they were darkness and nothing but darkness, they would not exist. Hence they live in a never-never land that is neither light nor darkness. 

In respect of tashbih, the creatures are light, but in respect of tanzih they are darkness. In other words, to the extent that things are similar to God, they are luminous, but to the extent that they are incomparable with God, they are dark. They must have some luminosity, or else they could not exist. 

To dwell in darkness (relative darkness, that is, since absolute darkness does not exist) is to dwell in distance from God; it is to be dominated by the divine qualities of majesty and wrath, which keep things far from God. To dwell in light is to live in nearness to God; it is to be dominated by the qualities of beauty and mercy, which bring things close to God. 

There is one light, and that light is God. There are many darknesses, since each creature represents darkness in relation to God. The deeper the darkness, the greater the distance from God. Absolute darkness does not exist, because it would be cut off from God in every respect. How can anything exist if it has no relationship whatsoever to the Real, which is the source of every quality? 

Created things dwell in distance from God, in difference, in otherness. This is to say that they dwell in relative darkness. Relative darkness has many modes and forms, since there are an infinite number of ways in which things can be different from God. "Nothing is like Him," but each thing is unlike him in its own unique way. 

Dwelling in difference means perceiving God from the perspective of tanzih and hence to be dominated by the attributes of severity, majesty, and wrath. The goal of religion is to bring about a movement from tanzih to tashbih, from distance to nearness, from difference to sameness, from manyness to oneness, from wrath to mercy, from darkness to light. 

The Koran frequently explains that God's goal in creation is to bring about unity, and often it employs the terms light and darkness to make this point. The broad significance of such verses becomes clear as soon as one grasps the meaning of tawhid. Notice that in the following verses light is one, since light is an attribute of God, but the darknesses are many, since darkness is an attribute that assumes many forms in keeping with the diversity of creation: 

Are the blind and the seeing man equal, or are the darknesses and the light equal? (13:16, 35:20) 

It is He who sends down upon His servant signs, clear explications that He may bring you forth from the darknesses into the light. (57:9) 

Why, is he who was dead, and We gave him life, and appointed for him a light to walk by among the people, as one who is in the darknesses, and comes not forth from them? (6:122) 

It is He who performs the salat over you, and His angels, that He may bring you forth from the darknesses into the light. (33:43) 

This last verse brings us back to the angels, who are created from light and are therefore able to assist God in giving light to the creatures who dwell in the visible world. 

Excerpted from the book "The Vision of Islam" by Sachiko Murata and William C. Chttick