Sri Aurobindo
Letters of Sri Aurobindo
Volume I - Part 2
A distinction1 has to be made between the soul in its essence and the psychic being. Behind each and all there is the soul which is the spark of the Divine – none could exist without that. But it is quite possible to have a vital and physical being supported by such a soul essence but without a clearly evolved psychic being behind it.
There is indeed an inner being composed of the inner mental, inner vital, inner physical,– but that is not the psychic being. The psychic is the inmost being of all and quite distinct from these. The word psychic is indeed used in English to indicate anything that is other or deeper than the external mind, life and body or it indicates sometimes anything occult or supraphysical; but that is a use which brings confusion and error and we have almost entirely to discard it.
The psychic being is veiled by the surface movements and expresses itself as best it can through the three outer instruments which are more governed by the outer forces than by the inner being or the psychic entity. But that does not mean that they are entirely isolated from the soul. The soul is in the body in the same way as the mind or vital – but the body is not this gross physical body only, but the subtle body also. When the gross body falls away, the vital and mental sheaths of the body still remain as the soul’s vehicle till these too dissolve.
The soul of a plant or an animal is not dormant – only its means of expression are less developed than those of a human being. There is much that is psychic in the plant, much that is psychic in the animal. The plant has only the vital-physical elements evolved in its form; the consciousness behind the form of the plant has no developed or organised mentality capable of expressing itself,– the animal takes a step farther; it has a vital mind and some extent of self-expression, but its consciousness is limited, its mentality limited, its experiences are limited; the psychic essence too puts forward to represent it a less developed consciousness and experience than is possible in man. All the same, animals have a soul and can respond very readily to the psychic in man.
The “ghost” of a man is of course not his soul. It is either the man appearing in his vital body or it is a fragment of his vital structure that is seized on by some force or being of the vital world for its own purpose. For normally the vital being with its personality exists after the dissolution of the physical body for some time only; afterwards it passes away into the vital plane where it remains till the vital sheath dissolves. Next one passes in the mental sheath, to some mental world; but finally the soul leaves its mental sheath also and goes to its place of rest. If the mental is strongly developed, then the mental being can remain and so also can the strongly developed vital, provided they are organised by and centred around the true psychic being – they then share the immortality of the psychic. But ordinarily this does not happen; there is a dissolution of the mental and vital as well as the physical parts and the soul in rebirth assumes a 
new mind, life and body and not, as is often supposed, a replica of its old nature-self. Such a repetition would be meaningless and useless and would defeat the purpose of rebirth which is a progression of the nature by experience, an evolutionary growth of the soul in nature towards its self-finding. At the same time the soul preserves the impression of what was essential in its past lives and personalities and the new birth and personality are a balance between this past and the soul’s need for its future2.