Bhagavad Gita Verse 41, Chapter 18

braahmankshatriyavishaam shoodraanaam cha parantapa |
karmaani pravibhaktaani svabhaavaprabhavairgunaihi || 41 ||
 
The duties of braahmans, kshatriyas, vaishyas and shoodras, O scorcher of foes, have been classified according to the gunaas, which have born of nature.
 
braahmankshatriyavishaam : braahmans, kshatriyas and vaishyas
shoodraanaam : of shoodras
cha : and
parantapa : O scorcher of foes
karmaani : duties
pravibhaktaani : have been classified
svabhaavaprabhavaihi : born of nature
gunaihi : gunaas
 
All of us are born with unique proportion of gunaas, with certain levels of sattva, tamas and rajas. These gunaas determine how we perceive the world, how we think about the world, and how we act and transact in the world. At a minimum, we want to live a healthy and materially prosperous life. Now we have seen that high levels of rajas and tamas can bring our downfall. But we cannot sit at home by ourselves, fearful of their impact. We have to engage with the world, transact with society. What should we do?
 
Shri Krishna says that we first need to understand our mental makeup. Once we have studied and analyzed our mental makeup, we can channel our inherent tendencies into productive actions that contribute to the well being society. If we perform our duty to society, society will ensure that we live a healthy life and prosperous life. After all, society is nothing but a larger manifestation of Ishvara. This the best and most practical career counseling advice given to us in the Gita.
 
So this section of shlokas educates us about analyzing our internal proportion of gunaas. This system of classification and analyzis is known as the varna system. We have to remind ourselves again to remove all prior conceptions and connotations of varna, which is improperly translated or construed as caste. The caste system as it stands today is not what was envisioned by the Vedas. The analysis of gunaas to understand one’s varna or one’s sphere of activity has to come from within. It cannot be imposed by anyone from the outside.