The spiritual world is a unified soul, one for all. By unifying with the others, everyone attains the same integral soul. In the article “600,000 Souls,” Baal HaSulam writes that there is nothing else in the world but one soul.
Every person attains this collective soul in an individual manner, according to his or her program or Reshimot (spiritual genes), just as at present, we observe the surrounding world and see it in our own way. I cannot compare the taste that I obtain from a certain food with how others taste it, or my impression of a painting that we both view. Everyone has impressions that match their Reshimot.
Even if we are standing in front of the same picture in spirituality, the same worlds and Partzufim, everyone receives an individual impression of it anyway. This uniqueness doesn’t vanish.
How do I unify with the integral soul? You do it by way of desires. Suppose I am in the center of the spiritual worlds: Assiya, Yetzira, Beria, Atzilut, Adam Kadmon (AK), or the world of Infinity. By exiting myself, my ego, and unifying with the others, I attain the dimension of the integral soul. In it, I perceive the spiritual world. The more I step out of my ego, acquiring the others’ Kelim (vessels), the more exalted world I perceive thereby.
How do I do that? I “purchase” new desires since I have only a point, an embryo, of the soul. The new desires that I gain while unifying with the others are, in fact, the Kli (vessel) of my soul.
From the 2nd part of the Daily Kabbalah Lesson 3/18/2011, “Introduction of The Book of Zohar”