Sri Aurobindo
Letters of Sri Aurobindo
Volume 1
Your series of experiences are very interesting by the constant (though interspersed) development they illustrate. Here two new significant elements have been added to the 
previous substance of the experience. The first is the very precise localisation of the uprush of the consciousness from the pit of the stomach – that is to say, from the navel or perhaps from just below it? The navel-centre (nābhi-padma) is the main seat of the centralised vital consciousness (dynamic centre) which ranges from the heart level (emotional) to the centre below the navel (lower vital, sensational desire centre). These three mark the domain of the vital being. It is therefore clear that it was your inner vital being which had this experience, and its intensity and vehemence was probably due to the whole vital (or most of it) being awake and sharing in it this time. The experience itself was psychic in its origin, but was given a strong emotional-vital form in its expression. I may add, for completeness, that the centre of the psychic is behind the heart and it is through the purified emotions that the psychic most easily finds an outlet. All from the heart above is the domain of the mental being – which also has three centres, one in the throat (the outward-going or externalising mind), one between the eyes or rather in the middle of the forehead (the centre of vision and will) and one above, communicating with the brain, which is called the thousand-petalled lotus, and where are centralised the thinking mind and higher intelligence communicating with the greater mind planes (illumined mind, intuition, Overmind) above.
The second new significant feature is the self-manifestation of the inner mind; for it was your inner mind that was watching, observing and criticising the vital being’s psychic experience. You found this clear division in you curious, but it will no longer seem curious once you know the perfectly normal divisibility of the different parts of the being. In the outer surface nature, mind, psychic, vital, physical are all jumbled together and it needs a strong power of introspection, self-analysis, close observation and disentanglement of the threads of thought, feeling and impulse to find out the composition of our nature and the relation and interaction of these parts upon each other. But when one goes inside as 
you have done, we find the sources of all this surface action and there the parts of our being are quite separate and clearly distinct from each other. We feel them indeed as different beings in us, and just as two people in a group can do, they too are seen to observe, criticise, help or oppose and restrain each other; it is as if we were a group-being, each member of the group with its separate place and function, and all directed by a central being who is sometimes in front above the others, sometimes behind the scenes. Your mental being was observing the vital and not quite easy about its vehemence, for the natural base of the mental being is calm, thoughtfulness, restraint, control and balance, while the natural turn of the vital is dynamism, energy thrown into emotion, sensation and action. All therefore was perfectly natural and in order.
I have no time to write more. But note how entirely conscious your inner being is when it does come into action,– which perfectly justifies what I wrote to you about it at a time when you were in despair over your incapacity and unfitness for Yoga! You will see now that I was right and your fits of despondency had no true ground – and also that I knew what was in you better than you yourself knew it.