Advaita Vedanta is probably the best known of all Vedanta schools. Advaita literally means "not two"; thus this is what we refer to as a monistic (or non-dualistic) system, which emphasises oneness. Its first great consolidator was Shankara (788-820). Continuing the line of thought of some of the Upanishadic teachers, and also that of his own teacher Gaudapada, Shankara expounded the doctrine of Advaita - a nondualistic reality. By analysing the three states of experience (waking, dreaming and deep sleep) he exposed the relative nature of the world and established the supreme truth of the Advaita: the non-dual reality of Brahman in which atman (the individual soul) and brahman (the ultimate reality expressed in the trimurti) are identified absolutely.