Krishna opens the fourth chapter with a revelation that reaches back to the beginning of creation itself. He tells Arjuna: this imperishable yoga, I first taught to Vivasvan, the Sun god. Vivasvan passed it on to Manu, and Manu taught it to King Ikshvaku. A chain of light, handed down like a lamp from one generation to the next.
What Krishna is saying is that the teaching of the Gita is not new. It is ancient wisdom that once flowed through the lineage of royal sages. These were not armchair philosophers but kings who ruled and fought and still lived by this knowledge.
There is something reassuring in this. The wisdom Arjuna is about to receive has already been tested by generations of seekers. Krishna is not inventing a theory on the battlefield. He is rekindling a flame that had been burning long before any of them were born.