Mental Sheath

Manomaya kosha is the third of the five sheaths of Vedantic thought, the sheath made of mind, manas, the faculty of thought, feeling, sensation and the ordinary restless mental activity that processes the input of the senses. It lies within the vital sheath and is subtler still, the layer of instinctive and emotional mind, of likes and dislikes, doubt and imagination.

In the nested scheme of the Taittiriya Upanishad the mental sheath governs the automatic mental life, the stream of thought and reaction, and it is distinguished from the deeper intellectual sheath of discernment that lies within it. The Vedantic analysis treats the mind here as still a covering of the self rather than the self, so that even thought and feeling, closely as we identify with them, are seen as layers to be observed and passed through in the inquiry toward the atman. The five koshas form the classical Indian model of the layered person, and the mental sheath is the middle of the five. The doctrine is ancient and central to Vedanta and yoga.

Vedantic thought overlays the five koshas with a second, coarser scheme of three bodies, or sharira: the gross, sthula sharira, the subtle, sukshma sharira, and the causal, karana sharira. Manomaya, the mental sheath, belongs to the subtle body along with the vital and wisdom sheaths, set apart from Annamaya, the food sheath, which alone is identified with the gross body and left behind at death.

Because Manomaya sits in the subtle rather than the gross body, the tradition holds it to persist beyond physical death, carrying the ordinary restless mind, its habits, doubts and reactions, forward until liberation dissolves the subtle and causal bodies as well; this is part of why Vedantic teaching treats disciplined control of Manomaya, quieting its restlessness, as necessary long before death, not only at the end of life.

Manomaya's restlessness is also what distinguishes it from Vijnanamaya, the wisdom sheath just within it: where Manomaya reacts automatically to sensory input, Vijnanamaya is held to discriminate and judge, and much of Vedantic practice is aimed at strengthening that discriminating sheath's hold over the more reactive mind beneath it. Twentieth century Theosophical writers later borrowed kosha terminology for a separately bounded scheme of subtle bodies, a distinct later system rather than a restatement of this teaching.

Sources The Principal Upanishads with Rainbow Body: A History of the Western Chakra System from Blavatsky to BrennanKurt Leland