At the moment when Israel stood at the foot of Mount Sinai, the heavens parted and the spirit of G-d descended from on high amidst thunder and lightning fire. In revealing Himself to the entire community of Israel, God in essence laid bare the hidden core of Kabbalistic truth which up to that point had been the privilege of a select few.
According to Kabbalistic tradition, the purpose of Creation is to provide God with a "dwelling place in the lower realms," a goal which achieves fulfillment through the channeling of Divine light into the progressively denser "vessels" of human thought, feeling, and deed, and from there into the rest of material reality.
The Kabbalah's attempt at bringing the mysteries of Creation into closer proximity of man's own experience has expressed itself perhaps most radically through the vehicle of Chassidic thought and tradition.
Chassidut advanced the focus of the mystical tradition beyond the realm of olamot ("worlds," the reality of space and time) into the sublimer realm of neshamot ("souls").
Hence, while Kabbalah is referred to in the Zohar as the "soul of the Torah," Chassidut has been coined the "soul of the soul of the Torah."