Joseph Priestley (13 March 1733 – 6 February 1804) was a theologian, Dissenting clergyman, natural philosopher, educator and political theorist. He is usually credited with the discovery of oxygen, which he dubbed "dephlogisticated air", having isolated it in its gaseous state. He also discovered several other gases, invented soda water and wrote on electricity.
He served as a minister in Nantwich (1758–61), and also established a school where he taught natural philosophy. It was here that he wrote the seminal work, The Rudiments of English Grammar. He was also a tutor at Warrington Academy (1761–67).
Priestley's metaphysical writings attempted to combine theism, materialism and determinism; these works are considered to be one of the main sources for utilitarianism. Besides Rudiments, his contributions to pedagogy include the invention of modern historiography. He advocated equal rights for religious Dissenters and helped to found Unitarianism in England.