Gnānam, vignānam, āstikyam, BrahmKarma svabhāvajam
Those with calmness, self-control, disciplined effort,
purity (of mind and body), forgiveness, righteousness,
knowledge, supreme knowledge (about Brahman),
and faith in God are fit for the duties of a Brāhmań
(Brāhmin).
Bhagavad Gitā, XVIII.42
Brāhmań-s were the intellectuals who became teachers and preachers. They learnt the scriptures and other arts and sciences, spent their lives running residential schools ( Gurukul-s) and performing religious ceremonies ( Yagna). Preservation of Védic traditions and knowledge was their duty. Brāhmań- s were very spiritual and lived a simple life following the highest moral and ethical principles to set a good example for the rest of the society. They were supported by the king, the wealthy, and the parents of their students.
There was no demand for any fees for their services. Some selected few would seat in the court of the king to advise him on moral and ethical issues.