Why did the Brahmans always quote …

In Purusha Sukta hymn in Rig veda it is mentioned how different caste came into existence and it is used frequently to prove the supremacy of the brahmanas in the fourfold caste system. It is one of the way how Brahmanas tried to put rest of the society under its wings, other was through the use rulers. Many a time these two groups have joined hands in history to rule the masses.
There could be many reasons for why Brahmanas did that or still does that. One basic reason could be through quoting sacreds hymn gives it a sacred meaning. It renders fear in the heart of the people, the notion of going to hell and heaven if one breaks the sacred code, thus making it easier to rule upn the ignorant masses.

Secondly by quoting the hymn it justifies what brahmanas do, it gives their activities a religious legitimacy. And it is the easiest way to do. Relgion is a tool that is easily understandable and something that to people make sense because it stops someone from questioning.

Thus we can see through above reason why Brahmanas would quote hymns to justify their position in the society.