The Zohar, Chapter “VaYaera (And the Lord Appeared),” Item 94: Of course he [Abraham] saw them, since they came down to earth in the form of people. They were certainly holy spirits, but when they come down to the world, they clothe in air and in elements of cover and wrapping and seem to people precisely in their form.
There are different ways to interpret this. We perceive reality in the desire to receive pleasure. Everything that we perceive as existing is the desire to receive pleasure that is manifested in matter. What does it mean that it’s “manifested in matter”? It means that reality is perceived in those senses in which I exist on my level.
To perceive beyond this level requires changing one’s properties. I perceive the Light in my desire to the extent of my similarity to the Light. It depicts various images and forms for me. What does it mean that, now, I exist in this world? It means that the Light shines in my properties and what I observe in them is my reality.
If the Light shines for me more and my properties change, I will rise to a higher level which is higher in quality and closer to the Light. By shining in my more corrected and improved properties, the Light will give me the perception of the upper rung or the Upper World. Everything is pictured in a person’s properties.