Bhagavad Gita Verse 1, Chapter 4

Shree Bhagavaan uvaacha:
imam vivasvate yogam proktavaanahamavyayam |
vivasvaan manave praaha manurikshvaakavebraveet || 1 ||
 
Shree Bhagavaan said:
I had declared this imperishable yoga to Vivasvaan. He told it to Manu, and Manu told it to Ikshvaaku.
 
imam : this
vivasvate : to Vivasvaan
yogam : yoga
proktavaan : declared
aham : I had
avyayam : imperishable
vivasvaan : Vivasvaan
manave : to Manu
praaha : told
manuh : Manu
ikshvaaku : to Ikshvaaku
abraveet : told
 
In this first shloka of the fourth chapter, Shri Krishna gives the paramparaa, or the tradition, of the knowledge of the Gita. When any ancient texts are revealed, their tradition or heritage is also revealed. However, Shri Krishna first says that this teaching is imperishable. It always existed and can never be destroyed.
 
Shri Krishna then begins the paramparaa. He says that had revealed the same knowledge a long time ago to Vivasvaan. Vivasvaan means the sun. The name Vivasvaan is derived from the sanskrit root vasa meaning one who resides very well, or also, one who illumines everyone. The sun can be considered the first student of karmayoga. Not only does he selflessly provide light to the world, he also never gets tired doing so.
 
The sun then gave this knowledge to Manu. Manu is the original ancestor, and is considered to be the first human being from whom all humans originated, like Adam in the Bible. Hence humans are called manu-shya.
 
Manu then gave this knowledge to Ikshvaaku, who was the first king in the solar dynasty or the "soorya-vansh". All these kings were kshatriyas or warriors. Shri Krishna highlights this point in order to make Arjuna, a warrior himself, better appreciate the teaching.
 
Now, Arjuna had a doubt. How could Shri Krishna, his best friend, have provided this knowledge to the sun? Arjuna will ask this question shortly. But first, Shri Krishna explained the need to resurrect this very ancient knowledge in the next shloka.
 
Footnotes
1. The symbolic interpretation of this shloka could be taken as follows: Vivasvaan is the light or the eternal essence that shines thought the intellect. Manu is the mind. Ikshvaaku is the senses. Therefore, the eternal essence pervades the body, mind and intellect.