Greek philosophers
Parmenides
Parmenides was a Greek pre-Socratic philosopher. He was born in 510 BC in the Greek colony of Elea (now Velia in southern Italy) and died in 450 BC.
Parmenides was one of the most important philosophers and Plato considered him the "father of philosophy". He was also the founder of the Eleian School, to which his pupils Zenon of Elea and Melissos belonged.
His works have not survived except for a few fragments. He was to write a verse work "On Nature" (Peri physeós). It is said to have had 3000 verses, of which only 150 have survived. The work was divided into three parts (preface, the way of truth, the way of appearance). The work is written in an unusually dense and economical language, making its interpretation very difficult.
Parmenides is taken as the first "critical" philosopher who is not content with ordinary sense knowledge. Knowledge, according to him, must be based on rational criticism, on the demand for indisputability, and on fixed concepts. This is a big difference from his predecessors who explained things by experience. Parmenides is therefore in fact the first theorist.