Quote of the day by Parmenides: 'What is, is; what is not, is not.'

Ancient Greek philosopher Parmenides, living in the late 6th and early 5th century BCE, fundamentally questioned existence. He asserted that "what is, is; what is not, is not," arguing that being is real, whole, and unchanging. This led him to conclude that change, motion, and multiplicity are mere illusions, with true knowledge attainable only through reason.