The principle of awareness, sentience, I-ness, the witness, the observer, that part of the being that experiences all things, yet is not touched or altered by the experience.
There are two explanations of Consciousness. Physicalists reduce it to a by-product of the activity of complex systems like brains or neural nets. Mystics consider that consciousness is primary, and matter and phenomena secondary. Of those, pantheists consider consciousness and the fundamental forces of nature the same, whereas Sophics and other religions consider that consciousness is the cause and predecessor of the cosmos.