Some interesting words from OSHO on AUM`
“…The deeper and slower the flow of breath, the more your navel center will develop. Every time you breathe, the breath hits the navel center. If the breath goes in and out from above the navel center, then slowly the center becomes idle, it becomes weak. The breath does not hit it.
In the old days people found some clues, a formula, for breathing. But man is so unintelligent that he starts repeating the formulas without seeing their meaning, without even understanding them. It is just like scientists finding a formula for water -- H20. They say that with the combination of both, hydrogen and oxygen, water is created. Two atoms of hydrogen and one atom of oxygen make the formula H2O. Now if a person starts repeating, "H2O, H2O", in the same way as people are repeating, "Rama, Rama, Aum, Aum", then we will say he is mad -- because what can happen by repeating a formula? The formula is only an indication about something. If you understand what it is about, then the formula is significant.
You can often hear people sitting and repeating the sound of Aum. They do not know that Aum is a formula like H2O. There are three letters in Aum. They are 'A', 'U', 'M'. Perhaps you may not have noticed that if you close your mouth and say 'Aa' loudly inside then you will feel the sound of 'A' resounding in your head. 'A' is an indication of the head center. If you say 'U' inside then you will feel the sound of 'U' resounding within your heart. 'U' is an indication of the heart. And if you say 'M' inside, the third part of Aum, then you will feel it resounding near your navel. 'A', 'U' and 'M' are three sounds indicating sounds of the head, the heart and the navel. If you say 'M', you will feel the whole force of it on the navel. If you say 'U', you will feel the force going to the heart. If you say 'A' then 'A' will resound in the head and disappear.