He used to be a great ruler named Kaushika, but somehow found his way to spiritual greatness instead, due to an argument over a cow.
It so happened that one day while marching across the country the king and his army stopped over at the house of VASHISHTHA the sage. They were treated to a slap-up banquet of such splendor that VISHVAMITRA wondered how on earth the sage could afford it.
Vash was happy to explain. He owned a magic calf named NANDINI which could grant wishes. Anything he desired was instantly available. Banquets no problem.
King Vish was impressed and immediately offered to buy the creature. Imagine what such a limitless magical resource could do for his military expenses budget. The army’s food bill would be reduced to nothing. He could wish for shiny new uniforms. And maybe even some magic weapons of mass destruction.
But VASHISHTHA wasn’t selling. Who on earth would willingly part with a magic cow? Especially such a cute and bountiful one. Vish offered riches beyond imagining. Then he offered riches beyond the imagining of imagining. Vash refused everything.
Driven to greedy desperation, Vish tried to snatch the cow by force. But this cow was not for moving and — helped by her holy mother KAMADHENU — she repelled all attempts. Vish went a bit mad and the cownapping escalated into a full-scale Vish vs Vash spiritual battle. He even fed his rival’s sons to some hungry demons, thereby causing the Vash descendants to lose caste for 700 generations or so. All to no avail.
Finally VISHVAMITRA realized his greed was leading him to the dark side. He surrendered, apologized, abandoned his military ways, gave up the kingdom and became a humble sage-in-training. After many tough trials he took his place among the RISHIS and is now a highly-regarded demi-deity of wisdom and peace. All thanks to a row over a cow.