Srimad Bhagavad-Gita :
Chapter-13. ( Kshetra-kshetrajna-vibhaga-yogam )
Contents of this chapter, continuity of the ideas of last seventh and eighth chapters only.
Four chapters From the 9th to 12th, may be considered as explanation of Arjuna's doubts clarifications and the strengthen his awareness of consciousness of tattvam-s.
Lord did not forget the prime idea of the eighth chapter.
After almost satisfying the mano-bhuddhi of his disciple ( Arjuna ), then Lord Lord returns to earlier idea.
Great Acharyas who see Srimad Bhagavad-Gita which has eighteen chapters, as the narration of 'Maha-vakyam' "Tattvamasi," divided the text into three parts of six chapters each.
"Of the 'Maha-vakyam' "Tattvamasi" the terms 'TAT' indicate "Paramatma," and 'TVAM' to "Jivatma" and 'ASI' to their oneness.
The first six chapters ( Prathamashtakam ) are about tvam ( jivatma ), next six chapters ( dvateeyashtakam ) about tat ( Paramatma ), after explaining these two parts in total till twelve chapters, the last six chapters ( triteeyashtakam ) will be the commentary of the term 'ASI.'
Now this thirteenth chapter onwards till eighteenth chapter will be the content of triteeyashtakam, it is said so.
To be continued ...