born 0441; 515 BC
Greek philosopher, leader of the Eleatics .
His general teaching has been reconstructed from the few surviving fragments of his lengthy verse composition On Nature . He held that the multiplicity of existing things, their changing forms and motion, are but an appearance of a single eternal reality, "Being." This doctrine, which was formulated as the principle that "all is one," entails that all claims of change or of non-Being are illogical. Because of his method of basing claims about appearances on a logical concept of Being, he is considered a founder of metaphysics . Plato 's dialogue Parmenides discusses his thought.