Without any duality of perceiver and per­ceived, there is no way a normal thought can survive; it vanishes. The phrase ‘single sphere of dharmakaya’ refers simply to this original wakefulness. It is called single or sole, meaning not a duality, whereas the normal thinking mind is dualistic, and is never called single. If this holding onto duality is not dissolved from within, there is the per­petuation of subject and object, perceiver and perceived. Another fa­mous phrase goes: ‘As long as duality does not become oneness, there is no enlightenment.’ When recognising, this duality is dissolved into oneneness.

-- Tulku Urgyen Rinpoche