Ocean of Consciousness!

One of the profound insights that one begins to get is the way in which 1) the levels of personal consciousness, 2) the stages of the mental process, and 3) the levels of the universe parallel one another. One comes to see that these three are functioning at the same levels of reality, which are none other than the levels of consciousness themselves. It is approximately like this:

Waking = Conscious = Gross = Vaishvaanara (A of OM Mantra)
Dreaming = Unconscious = Subtle = Taijasa (U of OM Mantra)
Deep Sleep = Subconscious = Causal = Prajna (M of OM Mantra)
Turiya = Consciousness Itself, permeating and being All (Silence of OM Mantra)

One of the other elegant and awesome insights is the way in which our own personality, mental and emotional processes operate:

Latent impressions begin to stir: We come to see, in direct experience of Yoga Meditation and Contemplation, how it is that there are latent impressions in the deep unconscious (the place of Deep Sleep), and how it is that consciousness drifts over these latent impressions, causing them to stir from the Causal level.

These impressions arise into internal action: Then we see the way these impressions then arise into action internally in the Unconscious (the Active Unconscious associated with unseen mental processes and the Dreaming Sleep level), forming many invisible thought processes, normally only experienced in dreams (this is similar to what psychology calls "primary process").

These stirrings come forward into the conscious: Then we see the intriguing way in which those stirrings in the Unconscious (U of OM) come forward into the Conscious, Waking state of reality (A of OM), along with the way in which the indriyas, the senses (jnanendriyas of smelling, tasting, seeing, touching, and hearing) and means of expression (karmendriyas of eliminating, procreating, moving, grasping, and speaking) come into play so as to relate to the external world.

We can observe the four functions of mind: We come to see how the four functions of mind interact within these levels (A, U, and M of OM), including Manas (sensory-motor mind), Chitta (storehouse of impressions), Ahamkara (I-maker or ego), and Buddhi (which knows, decides, judges, and discriminates).

Seeing all the levels permeated by consciousness: Most importantly, we come to see the way in which all of these levels are both permeated by, and are the manifestation of consciousness itself:

In Waking state (A of OM Mantra), there is consciousness.
In Dreaming state (U of OM Mantra) there is consciousness.
In Deep Sleep (M of OM Mantra), there is consciousness.
In active thinking (A of OM Mantra), there is consciousness.
In unconscious process (U of OM Mantra), there is consciousness.
In the latent storehouse (M of OM Mantra), there is consciousness.

Who we really are, is the consciousness itself: We come to see that who we really are, is the consciousness itself, not the forms which arise. We declare with conviction, what the sages have said all along, "I am not my thoughts! I am That I Am!"

Consciousness at three levels: That reality or presence of existence itself, that is in the three levels of bed of the river, flow of the river, and surface of the river.

• Subconscious: Our Subconscious wants, wishes, desires, attractions, and aversions (samskaras) are like those stones that form the bed of the river (M of OM)
• Unconscious: When consciousness moves across them, they come to life in the the flow of the Unconscious (U of OM), like the flow of the river, and
• Conscious: Some burst forth into the Conscious mind (A of OM), resulting in actions, speech, and conscious thoughts, like the action on the surface of the river.

Going beyond the three levels: Through practice, one gradually attains the ability to go beyond, or deeper than the various levels and thinking processes, to the direct experience of the source of the consciousness, symbolized by the Silence after the "A," "U," "M," of the OM.

The practice begins simply, is practiced sincerely and faithfully, and expands over time, with ever-increasing insights about the underlying truths contained in, and suggested by the OM. Meditation on OM (AUM) as an object of concentration, and Contemplation on its meaning work together in guiding one towards Self-realization.

Reference: Yogic Conscious Deep Sleep by Swami Jnaneshvara Bharati at http://www.swamij.com/yoga-nidra.htm