The teachings in the Upanishads have been interpreted in a number of ways, ranging from non-theistic monism to theistic dualism. In former, rituals are not necessary and a path of introspection and meditation is emphasized for the correct knowledge ("jnana") of self. In latter, it is the full and correct knowledge of a Vishnu avatar or Shiva or Shakti (Goddess) that is emphasized. In all its various interpretations, the paths are not necessarily mutually exclusive. A "Jnana yogi" may also practice "Karma yoga" or "Bhakti yoga" or both, and differing levels of emphasis.