When you wake up in the morning, consciousness dawns. In this state of being conscious, you perceive a body, mind and world. These are appearances only, not what you are. To identify oneself with any of those appearances gives rise to the notion of being a separate person, self or individual entity. This is the cause of all seeking, suffering and doubts.
Being conscious is a state that comes and goes. In sleep, unconsciousness or death, the experience of being conscious subsides. So it is clearly a transitory state. However, before you awoke and became conscious of anything else, including the fact of being conscious, you were there.
Consciousness happened to you who were there to experience it. Your original, fundamental position is prior to consciousness. This "prior to consciousness" identity that you are cannot be named at all. From this unnameable, non-conceptual source, which is your original, innate nature, arises the sense of conscious presence. This is also the sense of being, the experience that "I am", or the bare fact of knowing that you are. This is the first appearance or experience upon your original state.
Within this consciousness state emerges the mind, the body and the entire world of appearances. Little can be said about your original state because it is clearly beyond all concepts and even prior to consciousness. Some pointers that have been used are: non-conceptual awareness, awareness unaware of itself, pure being (beyond being and non-being), the absolute, the unmanifest, noumenon, cognizing emptiness, no thing - to name only a few. This non-conceptual awareness or being IS what you are. It is pure non-duality or unicity in which both subject and object are merged.
Just as the sun does not know light because it IS light, so you do not know your original nature (as an object) because you ARE THAT. It is forever beyond the grasp of concepts and subject-object knowledge. Yet it is entirely evident and inescapable as that in you (which is you) that allows you to say with utter certitude "I am" and "I know that I am". Even when those words subside, you ARE. Even when the consciousness that knows those words subsides, you ARE. Consciousness is the light of creation. But you, as the unnameable source, are the primordial awareness, being or no thing (call it what you will) in which consciousness comes and goes.
–John Archibald Wheeler