Sanathsujaatha was a devine sage. He was one of the four sons of the god of creation Brahma .
The other three were Sanaka, Sanandana and Sanathkumaara. ( !The last was the teacher of philosophy to Bheeshma (------- need be corrected ------ !). Sanathsujaatha is also known as Sanaathana. This quartet was instrumental in making the two door keepers Jaya and Vijaya of Vykuntham, in taking births three times as mortals , in the form of Hiranyaaksha and Hiranyakashipu firstly ,Raavana and Kumbhakarna secondly and Shishupaala and Danthavakthra lastly.
When Dhritharaashtra was tensely insomniaic
after Sanjaya's return from Paandavas , Vidura consoled him to his best but could not bring him to normalcy. Then, Vidura invoked to the sage Sanathsujaatha to teach some philosophical topics to Dhritharaashtra to relieve him of the pressure.
Those famous teachings were contained in this chapter hence the name
Sanathsujaatheeyam to it.
The scholars consider this chapter next to Geetha in philosophical standards. Pure Traditionalists oppose translation of such texts inti vernacular languages. That might be the reason why the famous Telugu poet Thikkana dropped this great chapter altogether in his translation work and epitomized the Geetha to the minimum.