Parmenides
Parmenides of Elea
Parmenides of Elea (in Southern Italy; active in the first half of the fifth century) founded the Eleatic School and taught that Being (or Existence) must be unchanging and unmoving, and so the changing world registered by our senses has no reality whatsoever and cannot be known at all (how can you "know" an illusion?). Only reason, without the senses, can lead us to the truth about existence, which neither moves nor changes nor has any parts. This is diametrically opposed to Heraclitus?s view, and like Heraclitus?s thought, the Eleatic school effectively mucked up Greek speculation about the nature of things for quite a few decades. However, the Parmenidean idea of the nature of reality would become the basis of Plato?s thinking and would later become the foundation of the Christian theology of God.