Chapter IV Sloka 04

AjuRn %vac,
Apr< -vtae jNm pr< jNm ivvSvt>,
kwmetiÖjanIya< TvmadaE àaeKtvainit.

arjuna uv˜ca |
aparaÕ bhavato janma 
paraÕ janma vivasvata× |
tvam˜dau proktav˜niti ( 4|04)||

Arjuna said :
Later on was Thy birth, and prior to it was the birth of Vivasvan (the Sun); how am I to understand that you taught this Yoga in the beginning?

Commentary: your birth took place later in the house of Vasudeva; Vivasvan or Vivasvat (the sun) was born earlier in the beginning of evolution. How am I to believe that you taught this Yoga in the beginning to Vivasvan, and that you, the self-same person, has now taught it to me? 

I am not able to reconcile this. Be kind enough to enlighten me, O my Lord!