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In biya/lower worlds there isn't revelation of the of the actual line of light/kav, just a reflection of it.
Sunshine represents the sun. light of a candle represents the fire of the candle. Each has an essence, but the sunlight has a higher essence.
Between atzilus and biya is a curtain. Atzilus does not have a curtain above it. Yet it is a 'worldly' state. It represents overall the level of chochmah. Biya represents bina. Between binah and chochmah there is a gap. Binah cannot relate to the purity that chochmah engenders. This is like sight and hearing. Sight connects to the reality itself. Hearing has a gap, 'you are talking about something'.
Sight sees the thing itself, but it is not the thing itself. It shows the reality of it. There is a small gap, but no parsah/curtain/obstacle. We say shma with closed eyes. We acknowledge the truth that is inherent. Then with open eyes it is the same truth,but now you're looking at it. Atzilus is like this second stage. We are looking at that which we know with closed eyes, but it is not the same, now we are observing it.