Sri Aurobindo
Letters on Yoga
1. The Supramental Evolution
I have not said that everything is falsehood except the supramental Truth. I said that there was no complete Truth below the supramental. In the overmind the Truth of supermind which is whole and harmonious enters into a separation into parts, many truths fronting each other and moved each to fulfil itself, 
to make a world of its own or else to prevail or take its share in worlds made of a combination of various separated Truths and Truth-forces. Lower down in the scale, the fragmentation becomes more and more pronounced, so as to admit of positive error, falsehood, ignorance, finally inconscience like that of Matter. This world here has come out of the Inconscience and developed the Mind which is an instrument of Ignorance trying to reach out to the Truth through much limitation, conflict, confusion and error. To get back to overmind, if one can do it completely, which is not easy for physical beings, is to stand on the borders of the supramental Truth with the hope of entry there.
Current publication:
Sri Aurobindo. Letters on Yoga // SABCL.- Volume 22. (≈ 28 vol. of CWSA).- Pondicherry: Sri Aurobindo Ashram, 1971.- 502 p.
Other publications:
Sri Aurobindo. Letters on Yoga. I // CWSA.- Volume 28. (≈ 22 vol. of SABCL).- Pondicherry: Sri Aurobindo Ashram, 2012.- 590 p.
[Largest or earliest found passage: ] Patel, Govindbhai. My Pilgrimage to the Spirit.- Second Revised Edition.- Ahmedabad, 1977
Sri Aurobindo. The Riddle of this World: Letters.- Pondicherry: Sri Aurobindo Ashram, 1973.- 72 p.