One thing that gains Parmenides a philosophers' merit-award, as the first principles story explained, is the idea of proving his point. Like others at the time, he wrote in magnificent poetry. That was nothing new and nothing strange. But what he wrote didn't just sound good or seem plausible; it also took the reader step by step through an argument. It aimed to demonstrate, without a shadow of doubt, that the conclusion had to be true if the initial assumptions were correct.

Presocratic Philosophy: A Very Short Introduction (2004) - Ch. 2 : Puzzles about first principles