The real nature of the soul is described in the Bhagavad Gita as ‘INDESTRUCTIBLE’. Consciousness is spread throughout the body. It is this which differentiates between a dead and a living being. Each and every body is the embodiment of an individual soul and the symptom of the soul’s presence is perceived as individual consciousness.
According to the Mundaka Upanishad this atomic soul which is 1/10000 the size of the tip of the hair on your head is situated in the heart of every living entity. Life of an entity is due to the light of the ātma. Medical science has proven that the heart is the seat of all energies in the body.
As a person puts on new garments, giving up old ones, the soul similarly accepts new material bodies, giving up the old and useless ones.
It is said that the soul is invincible, inconceivable and immutable. Knowing this you should not grieve for the body.
Therefore the body itself is unimportant and we must cleanse this bodily concept of life. That is I am spirit soul, part and parcel of the Supreme Lord. Just as how a machine is looked after by maintaining it similarly the body must be maintained to perform the prescribed duties.