The Kalacakra (Wheel of Time) tantra is a system of Vajrayana Buddhist mysticism that developed in India during the 11th century. Like all forms of Vajrayana Buddhism, the Kalacakra utilizes theurgy as a path of soteriological apotheosis. The basic concept underlying the Kalacakra system is the ancient idea of the identity
of the macrocosm (the universe) and the microcosm (the soul). Cosmos and soul form an integrated entity that serves as the basis for the soteriology of the Kalacakra yoga. Thus the entire subject matter of the Kalacakra tantra is presented under five categories: cosmos, soul, initiation, practice, and gnosis. The Kalacakra is also described in terms of three Kalacakras: the Outer, Inner, and Other Kalacakras. The Outer Kalacakra is the cosmos; the Inner Kalacakra is the soul; and the Other Kalacakra is the path of apotheosis consisting of initiation, practice, and gnosis.