It is found in the "Trikaya" doctrine of Mahayana Buddhism, in descriptions for the Dalai Lama in Tibetan Buddhism, and many ancient cultures. The manifest embodiment is sometimes referred to as an incarnation. The translation of avatar as "incarnation" has been questioned by Christian theologians, who state that an incarnation is in flesh and imperfect, while avatar is mythical and perfect. The theological concept of Christ as an incarnation, as found in Christology, presents the Christian concept of incarnation. According to Oduyoye and Vroom, this is different from the Hindu concept of avatar because avatars in Hinduism are unreal and is similar to Docetism. Sheth disagrees and states that this claim is an incorrect understanding of the Hindu concept of avatar. Avatars are true embodiments of spiritual perfection, one driven by noble goals, in Hindu traditions such as Vaishnavism. The concept of avatar within Hinduism is most often associated with Vishnu, the preserver or sustainer aspect of God within the Hindu Trinity or Trimurti of Brahma, Vishnu and Shiva. Vishnu's avatars descend to empower the good and fight evil, thereby restoring Dharma. Traditional Hindus see themselves not as "Hindu", but as Vaishnava (Worshippers of Vishnu), Shaiva (Worshippers of Shiva), or Shakta (Worshipper of the Shakti). Each of the deities has its own iconography and mythology, but common to all is the fact that the divine reality has an explicit form, a form that the worshipper can behold. An oft-quoted passage from the Bhagavad Gita describes the typical role of an avatar of Vishnu: The Vishnu avatars appear in Hindu mythology whenever the cosmos is in crisis, typically because the evil has grown stronger and has thrown the cosmos out of its balance. The avatar then appears in a material form, to destroy evil and its sources, and restore the cosmic balance between the ever-present forces of good and evil. The most known and celebrated avatars of Vishnu, within the Vaishnavism traditions of Hinduism, are Krishna, Rama, Narayana and Vasudeva. These names have extensive literature associated with them, each has its own characteristics, legends and associated arts. The Mahabharata, for example, includes Krishna, while the Ramayana includes Rama. The Bhagavata Purana describes Vishnu's avatars as innumerable, though ten of his incarnations Dashavatara are celebrated therein as his major appearances.