Gradually, as you get to know the unifying force working in the whole of creation, you thereby replace the instruments of your perception: the heart and the mind. You become more responsive and begin to better comprehend what is going on and understand the Creator’s actions.
You suddenly see an enormous world, which is much broader, deeper, and more complex in all its angles and aspects. All of this becomes different in relation to you. But later you will understand that it is you who is changing, and outside of you, everything remains the same.
Later, you will find out that all you are seeing is only the Creator. It is so because there is none else beside Him. And what you see as the world is just your shadow over Him, and it is so until you will have reached the condition when this shadow disappears.
In other words, to reach adhesion with the Creator, we must undergo multiple changes. In your perception, these alterations are called the worlds of Assya, Yetzira, Beriah, Atzilut, Adam Kadmon, and the World of Infinity. These are degrees of your perception of reality that are shown to you in its much more authentic form.
So, what did change? Only your perception. You alter your sensory organs and witness how gradually the Creator is being revealed to you, how the image of the world acquires much sharper characteristics, becomes real, constant, and eternal. It all depends on the place you are observing it from in relation to the Light of Infinity.
Then, you begin to understand that the shadow you saw on the Creator, all of these concealments, the worlds, all of this was for your own good. At least, you saw some silhouettes, a certain drawing that you needed to erase, saw that you needed to become similar to the Creator within this shadow, to make it disappear.
From a Lesson 11/26/10, Baal HaSulam’s Letter #151