The phrase "central being" in our yoga is usually applied to the portion of the Divine in us which supports all the rest and survives through death and birth. This central being has two forms-above, it is the Jivatman, our true being, of which we become aware when the higher knowledge comes, -below, it is the psychic being which stands behind mind, body and life. The Jivatman is above the manifestation in life and presides over it; the psychic being stands behind the manifestation in life and supports it.

  The natural attitude of the psychic being is to feel itself as the Child, the Son of God, the Bhakta; it is a portion of the Divine, one in essence, but in the dynamics of the manifestation there is always even in identity a difference. The Jivatman, on the contrary , lives in the essence and can merge itself in identity with the Divine; but it too, the moment it presides over the dynamics of the manifestation, knows itself as one centre of the multiple Divine, not as the Parameshwara.
                    

 SRI AUROBINDO, On Yoga, II, tome I, part 1,5
                                

There is and can be no psychic being in a non-evolutionary creature like the Asura; there can be none in a god who does not need one for his existence. ...If any being of the typal worlds wants to evolve, he has to come down to earth and take a human body and accept to share in the evolution. It is because they do not want to do this that the vital beings try to possess men in order that they may enjoy the materialities of physical life without having the burden of the evolution or the process of conversion in which it culminates.
                  

   SRI AUROBINDO, On Yoga, II, tome I, part 1,6