Kabbalah's definition varies according to the tradition and aims of those following it, from its religious origin as an integral part of Judaism, to its later Christian, New Age, and Occultist syncretic adaptations. Kabbalah is a set of esoteric teachings meant to explain the relationship between an unchanging, eternal, and mysterious Ein Sof (no end) and the mortal and finite universe (God's creation). While it is heavily used by some denominations, it is not a religious denomination in itself. It forms the foundations of mystical religious interpretation. 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 thereby attain spiritual realization.