As-Salaam alaikum,

Sometimes, Sayyadi Ibn al-Arabi, may Allah be Merciful to him, uses the analogy of light to describe how Allah Ta'ala manifests and is known. We do not see light as such, although it certainly is needed for us to see anything at all. What we see is the reflection of light, the reflection off the trees, the waters, the air, etc...

So, light is the necessary substance pervading and illuminating all things, but we see only the reflections of it or how it manifests for us. So, Allah is only known by reflection, but subsists in everything, and "None knows Allah but Allah." We must realize that we cannot know Allah is His Essence, just as we cannot see the light in its purity; but we can recognize its reflections.