The thirteenth chapter of the Bhagavad Gita is "Ksetra Ksetrajna Vibhaaga Yoga". The word "kshetra" means "the field", and the "kshetrajna" means "the knower of the field". We can think of our material body as the field and our immortal soul as the knower of the field. In this chapter, Krishna discriminates between the physical body and the immortal soul.
