Shrimad Bhagavad Gita As It Is -Shri Shrimad A.C Bhaktivedanta Swami Prabhupada
Contents of the Gita Summarized
Chapter 2: Verse-17
avinasi tu tad viddhi
That which pervades the entire body you should know to be indestructible. No one is able to destroy that imperishable soul.
This verse more clearly explains the real nature of the soul, which is spread all over the body. Anyone can understand what is spread all over the body: it is consciousness. Everyone is conscious of the pains and pleasures of the body in part or as a whole. This spreading of consciousness is limited within one’s own body. The pains and pleasures of one body are unknown to another. Therefore, each and every body is the embodiment of an individual soul, and the symptom of the soul’s presence is perceived as individual consciousness. This soul is described as one ten-thousandth part of the upper portion of the hair point in size.The Svetasvatara Upanisad  confirms this:
“When the upper point of a hair is divided into one hundred parts and again each of such parts is further divided into one hundred parts, each such part is the measurement of the dimension of the spirit soul.” Similarly the same version is stated:
- avinasi=imperishable; tu=but; tat=that; viddhi=know it; yena=by whom;
sarvam=all of the body; idam=this; tatam=pervaded; vinasam=destruction; avyayasya=of the imperishable; asya=of it; na kascit=no one; kartum—to do; arhati=is able.