“The question to which we always return is why the pure soul came to this world.
Why did it descend from where it had stood before God to a world where the majority of the world is evil?
Several answers to this question are all based on the idea that this world’s physicality, inasmuch as it is low and impervious to sanctity, contains as well the power to stand firm before the divine presence and the ability to then absorb all the holiness that the upper worlds are not able and equipped to accept.
In this world, we must work particularly hard.
We must battle simply to recognize the divine being.
In this world, only the rare individual succeeds in clinging to God, an accomplishment that is the result of unusually intense service.
Yet, in the end, this world will receive a divine revelation higher than that experienced by any other world, literally of an infinite nature.”
From Understanding the Tanya, p. 223 by Rabbi Adin Steinsaltz