Empedocles (/ɛmˈpɛdəkliːz/; Greek: Ἐμπεδοκλῆς [empedoklɛ̂ːs], Empedoklēs; c. 490 – c. 430 BC) was a Greek pre-Socratic philosopher and a citizen of Acragas (Agrigentum), a Greek city in Sicily. Empedocles' philosophy is best known for originating the cosmogenic theory of the four classical elements. He also proposed forces he called Love and Strife which would mix as well as separate the elements. These physical speculations were part of a history of the universe which also dealt with the origin and development of life.