Chapter 13 of the Gita explores the relationship between the body and the spirit. The Lord explains that the body is called the field and that the spirit is the knower of the field. Our spirit is the glow of God. It is the spark of creation that exists beyond our physical, emotional or intellectual being.
In this chapter Lord Krishna discusses the role of knowledge in human existence. He describes knowledge, the opposite of ignorance, as many good things and particularly as awareness of God.
The ultimate purpose of knowledge is for us to reach the state of enlightenment which enables us to become one with God.
See The Gita, A New Translation of Hindu Sacred Scripture, by Irina Gajjar.