In Hindu philosophy, a modified form of immortality is ascribed even to the body of every living being. Of course, it is not the material body (sthula sharira) born out of the union of the parents. It is called the subtle body (linga deha, linga sharira, Sukshma sharira or karana sharira).
In Samkhya philosophy, sthula sharira is supposed to be
composed of eighteen tattvas (elements). They are the three elements of
internal organ (antahkarana), viz., intellect (buddhi), ego feeling (ahamkara)
and mind (manas); the jnanendriya (five cognitive senses), i.e. the organs of
sight, sound, smell, taste and touch; the karmendriyas (five motor organs),
such as hands, feet, speech organ, excretory and genitive organs; and the tanmatras
(five subtle elements), such as tanmatras of sabda (sound), sparsha (touch),
rupa (sight), rasa (taste) and gandha (smell).
In the Vedanta school, the subtle body is said to be
composed of seventeen and not eighteen elements. Vedantins do not believe in
the existence of the tanmatras (five subtle elements), but instead include the
five vital vayus (airs) as forming part of the subtle body (The forms of air
are – prana, apana, vyana, udana and samana). They also do not take ahamkara as
a separate element and include it in the mind (manas).
The subtle body has no beginning in time. It is in existence
since the beginning of the universe. Thus, it is said to be anadi. Just as each
soul is anadi, the subtle body attached to it is anadi too. The relation of
togetherness between them (samyoga) is also anadi like its cause, that is
ignorance (avidya). At the time of death, the self, along with the subtle body,
leaves the dead individual and gets associated with another gross body (sthula
sharira) which is being born. This process of transmigration is described in
detail in the Samkhya Karika of Ishwarakrishna (39-42).
The motion of subtle body is necessarily associated with the
notion of transmigration. For rebirth to be possible, the subtle body must be
believed to be endowed with a kind of immortality. But this immortality cannot
be like that of the soul, and the subtle body cannot be supposed to be Ananta (endless),
although there is no difficulty in taking it to be anadi. An endless subtle
body would make liberation (moksha or mukti) impossible. The subtle body is
supposed to come to an end and merge into its material cause, i.e. prakriti, at
the event of liberation of the self, due to the cancellation of avidya with the
arousal of atmajnana (self-knowledge). Thus, the immortality of the subtle body
is different from that of the self and God.
The subtle body is supposed to be the storehouse of the
traces of all past experiences gathered over all past lives. This is called
karmasaya. It binds the self to the cycle of rebirths. Karmasaya and its
binding effect is overcome by atmajnana. Thereby the self is released from bondage.
But that does not cause the innumerable other selves to be released from their own
subtle bodies which continue to bind them due to their own karmasaya.
In Yogasutra of Patanjali, the notion of the subtle body is
not mentioned at all. In Yoga philosophy, the chitta (internal organ) is supposed
to perform all the functions of the subtle body, such as gaining, storing and
reviving or remembering experience of the present and the past births. Here the
modified form of immortality which the subtle body is supposed to possess is
ascribed to chitta. At the time of liberation, chitta is supposed to merge into
prakriti, leaving the self alone and free of bondage. That is called
savrupavastha of the soul.