Kabbalah (Hebrew: קַבָּלָה, lit. "receiving") is a discipline and school of thought concerned with the mystical aspect of Judaism. It is a set of esoteric teachings that is meant to explain the relationship between an infinite, eternal and essentially unknowable Creator with the finite and mortal universe of His creation. In solving this paradox, Kabbalah seeks to define the nature of the universe and the human being, the nature and purpose of existence, and various other ontological questions. It also presents methods to aid understanding of these concepts and to thereby attain spiritual realization. Kabbalah originally developed entirely within the milieu of Jewish thought and constantly uses classical Jewish sources to explain and demonstrate its esoteric teachings. These teachings are thus held by kabbalists to define the inner meaning of both the Tanakh (Hebrew Bible) and traditional rabbinic literature, as well as to explain the significance of Jewish religious observances.