The Bhagavad Gita is divided into three groups of six chapters each. The first six chapters correspond to the great non-dual saying teaching: Thattwamasi you are that. So they are about self-knowledge and who am I? That's the question there. Next six chapters, seven to twelve are about that, God. And then chapters 13 to 18,. the identity, you are that, the true nature of the mystery of God explained or shown what that is and that is your own nature.