What we call “essence of mind” is the actual face of unconditioned pure awareness, which is recognised through receiving the guru's blessings and instructions. If you wonder what this is like, it is empty in essence, beyond conceptual reference; it is cognisant by nature, spontaneously present; and it is all-pervasive and unobstructed in its compassionate energy. This is the rigpa in which the three kayas are inseparable.

-- Mipham Rinpoche