Two important letters

of Sri Aurobindo

concerning "The Synthesis of Yoga"

and the word "Supermind" in "The Yoga of Self-Perfection"

At the time when the last chapters of "The Synthesis of Yoga" were written in the Arya [ = 1920-1921], the name "Overmind" had not been found, so there is no mention of it.
What is described in those chapters is the action of the Supermind when it descends into the Overmind plane and takes up the Overmind workings and transforms them.
The highest Supermind or Divine Gnosis existent in itself, is something that lies beyond still and quite above.
It was intended in latter chapters to show how difficult even this was and how many levels there were between the human mind and Supermind and how even Supermind descending could get mixed with the lower action and turned into something that was less than the true Truth.
But these latter chapters were not written.

April 13, 1932

*

"The Synthesis of Yoga" was not meant to give a method for all to follow.
Each side of the Yoga was dealt with separately with all its possibilities, and an indication as to how they meet so that one starting from Knowledge could realise Karma and Bhakti also and so with each path.
It was intended when the Self-Perfection was finished, to suggest a way in which ALL could be combined, but this was never written.

May 18, 1936

Sri Aurobindo

in "The Synthesis of Yoga" - Appendix
SABCL Volume 21- Pages 899
published by Sri Aurobindo Ashram - Pondicherry
diffusion by SABDA
or

Lotus Light Publications U.S.A.