Archelaus

an ancient Greek philosopher, a pupil of Anaxagoras. He may have been a teacher of Socrates. 

His doctrine could be extracted from other writers, however, none of his fragments have survived. 

Motion would be the result of hot and cold with their opposition. The separation of hot and cold was the principle of motion, as he asserted. From this point he endeavored to explain the beginning of the Earth, animals and humans. 

Archelaus believed in an Earth that was flat, however, was depressed in the middle. It cannot be absolutely level since the Sun does not rise and set at the same time everywhere. 

He said the Sun was the largest of the stars.