Simplify the following text for a Grade 9 native English-speaking person.
Original: Empedocles was a Greek pre-Socratic philosopher and a person who lived in Agrigentum , a Greek colony in Sicily .
Simplified: Empedocles ( ; EmpedoklÄ `` s ca . 490 â `` 430 BC ) was a Greek pre-Socratic philosopher and a citizen of Agrigentum , a Greek city in Sicily .