The works of Joseph Priestley include contributions in the fields of philosophy, political theory, and education. A British natural philosopher and Dissenting clergyman, Priestley is best known for his discovery, simultaneously with Antoine Lavoisier, of oxygen gas. A member of marginalized religious groups throughout his life and a proponent of what was called "rational Dissent," he advocated religious toleration and equal rights for Dissenters. Priestley argued for extensive civil rights in works such as Essay on the First Principles of Government, believing that individuals could bring about progress and eventually the Millennium; he was the foremost British expounder of providentialism. Priestley made significant contributions to education, publishing, among other things, The Rudiments of English Grammar, a seminal work on English grammar. Throughout his life, Priestley was also known as a natural philosopher. His scientific reputation rested on his writings on electricity, his invention of soda water, and his discovery of 10 previously unknown "Airs" (gases), that he reported about from 1774–1786 in a giant book of 6 volumes: Experiments and Observations on Different Kinds of Air. (Full list...)