Archelaus (/ɑrkɪˈleɪəs/; Greek: Ἀρχέλαος; 5th century BCE) was an Ancient Greek philosopher, a pupil of Anaxagoras, and may have been a teacher of Socrates. He asserted that the principle of motion was the separation of hot from cold, from which he endeavoured to explain the formation of the Earth and the creation of animals and humans.