Simplify the following text for a Grade 10 native English-speaking person.
Original: Joseph Priestley ( 13 March 1733 ( Old Style ) â `` 6 February 1804 ) was an 18th-century English theologian , Dissenting clergyman , natural philosopher , educator , and political theorist who published over 150 works .
Simplified: Joseph Priestley ( 13 March 1733 â `` 8 February 1804 ) was an English chemist , philosopher , clergyman , and teacher .