The change of the consciousness is the necessary thing without it there canbe physical siddhi. But the fullness of the supramental change is not possible, if the body remains as it is, a slave of death, disease, decay, pain, unconsciousness and all the other results of the ignorance. If these are to remain the descent of the supramental is hardly necessary for a change of consciousness which would bring mental-spiritual union with the Divine, the overmind is sufficient, even the Higher Mind is sufficient. The supramental descent is necessary for a dynamic action of the Truth in mind, vital and body. This would imply as a final result the disappearance of the unconsciousness of the body; it would not be subject to decay and disease. That would mean that it would not be subject to the ordinary processes by which death comes. If a change of body had to be made, it would have to be by the will of the inhabitant. This (not an obligation to live 3000 years, for that too would be a bondage) would be the essence of physical immortality. Still, if one wanted to live 1000 years or more, then supposing one had the complete siddhi, it should not be impossible.

Immortality, it cannot come if there is attachment to the body, for it is only by living in the immortal part of oneself which is unidentified with the body and bringing down its consciousness and force into the cells that it can come.

This knowledge was now made a cosmos' seed:
This seed was cased in the safety of the Light,
It needed not a sheath of Ignorance.
Then from the trance of that tremendous clasp
And from the throbbings of that single Heart
And from the naked Spirit's victory
A new and marvellous creation rose.