Why the breath?
The cravings, the aversions, the ignorance is at the deep levels of the mind-body phenomena.
The conscious mind is not aware of the processes at work deep inside.
The unconscious midnd is continuously operating deep inside.
When asleep the unconscious mind is still working.
The dreams are on the interface between the conscious and the unconscious mind but happen when asleep.
How to observe the unconscious mind when conscious?
The Breath is one process, unlike others, that can be controlled by the conscious and by the unconscious.
When deep processes are in action like the generation of passion or anger the breath becomes hard and hot. So by observing the breath it is possible to observe the deeper processes.
The breath is a bridge between the conscious and the unconscious.
Why the nose?
The aim is to sharpen the awareness and to study the truth as it is.
In the area of the nose it is possible to study realities that are there all the time. It is a study of truth. This must be equanimous. This takes practise. It takes work. There is no magic. Old habit patterns must change.
In the area of the nose the point of focus can be narrowed so that over time the mind becomes very sharp and focused. (then it is possible to start the practice of vipassana.)
A study of the natural breath, as it is, moment to moment, in the area of the nose is a study of the deepest parts of the mind and body.
When the equanimous awareness is established the deepest impurities start to move. At this time it is important to recognise that the unpleasant sensations (and pleasant sensations) are to be used as a tool to establish and maintain equanimity and in doing so these solidified seemingly permanent impurities start to dissolve, rise, and pass away.
But to get there it is essential to first practise anapana. Do so now.
Be Happy.