text: The triad appears in Maitrayaniya Upanishad, for the first time in recognized roles known ever since, where they are deployed to present the concept of three Guṇa – the innate nature, tendencies and inner forces found within every being and everything, whose balance transform and keeps changing the individual and the world. It is in the medieval Puranic texts, Trimurti concepts appears in various context, from rituals to spiritual concepts. The Bhagavad Gita, in verses 9.18, 10.21-23 and 11.15, asserts that the triad or trinity is manifestation of one Brahman, which Krishna affirms himself to be. However, suggests Bailey, the mythology of triad is "not the influence nor the most important one" in Hindu traditions, rather the ideologies and spiritual concepts develop on their own foundations. The triad, with Brahma creating, Vishnu preserving and Shiva destroying, balances the functioning of the whole universe.
  Avatars of Hindu deities
  Hindu mythology has nurtured the concept of the avatar (avatāra), which represents the descent of a deity on earth. This concept is commonly translated as "incarnation", and is an "appearance" or "manifestation".
  The concept of the avatar is most developed in Vaishnavism tradition, and associated with Vishnu, particularly with Rama and Krishna. Vishnu takes numerous avatars in Hindu mythology. He becomes female, during the Samudra Manthana, in the form of Mohini, to resolve a conflict between the devas and the asuras. His male avatars include Matsya, Kurma, Varaha, Narasimha, Vamana, Parashurama, Rama, Krishna, Buddha, and Kalki. In some lists, Balarama replaces the Buddha. Various texts, particularly the Bhagavad Gita, discuss the idea of an avatar of Vishnu appearing to restore the cosmic balance whenever the power of evil becomes excessive and causes persistent oppression in the world.