Reaching the Subtle through the Gross

                                Consciousness, supreme Intelligence or ultimate Reality has a two-fold expression to make its potential evident. One is praana, the cosmic power, engendering all external and internal movements, vibrations and activities, with the necessary order and sequence. The other is the knowing power or ideation, which designs and initiates all these activities.
The knowing and acting facets are inseparable, like heat and brilliance of fire. To design and give rise to an activity is the prerogative (called sankalpa) of the knowing power (chit). To translate sankalpa in the form of the requisite movement, vibration and activity is the role of praana. Both work in parallel and in mutuality.
Because of the mutuality of chit and praana, breathing-regulation can also regulate the mind. Bhushunda narrates beautifully the effects of praanaayaama on the mind:

"By following assiduously inhalation and exhalation, and perceiving the supreme Self as a result, I have, O great ascetic, attained to the primordial abode free of all torment. Remembering astutely the conjunction of inhalation and exhalation, I am rejoicing in my own inmost Self, and hence am living free of all bodily and mental discomfort."

To begin with, the practice consists of silently following the breathing – both inhalation and exhalation. But by this, before long, the attention is bound to reach the subtle inner centre, where the inhalation ends and exhalation commences. In reality no gap between the two is possible. It is a point of conjunction of both.
The inflow becomes the outflow with the mediation of a third factor. This is the subtle conscious Presence that comprehends the repeated terminations and commencements. Be sure that the material, insentient air, cannot manage the transition on its own. The air that flows is inert. To end inhalation and trigger the reverse process, something, the maker of both, must be there. That is the Self. It is from the Self that movement and vibration emerge, and also the sensing of these. Get to that sentient Presence.
Medical science says that for every beat of the heart, the brain provides a stimulus. Heart is only a biological machine. To operate it, there is need for a conscious Presence. Follow the inflow; meditate upon it. What moves is the breath, but what is revealed and reached at is the most subtle sentience reigning within. Thus, praanaayaama grows into the subtle process of inner cognition, and enlightenment.