c. 515-480 B.C.

Most important of ancient Greek philosophers prior to Socrates. He was the first to address the nature of being and the problem of change. He argued that all existing things do not change inasmuch as all things that exist always have existed, and nothing can become anything other than it is. Although our senses indicate otherwise—in other words, that things change—Parmenides argued that such perceived change was an illusion.