Born into a poor family in a village near Yorkshire, England, Priestley lost his mother at an early age and was sent to live with his aunt, a devout Protestant. He was educated at religious schools that endorsed nonconformist beliefs; he never formally studied science, but he did excel as a scholar of languages, logic, and philosophy. Priestley became a country preacher, but eventually turned to teaching. While employed at the Warrington Academy in the 1760s, he argued that school curriculums should reflect contemporary discoveries, rather than following outdated classical models. In 1762 Priestley married Mary Wilkinson, the sister of one of his schoolmates.

In 1766 Priestley visited London, England, and met Benjamin Franklin, who was trying to settle a dispute between the American colonies and the British government.

Soon after meeting Franklin, Priestley took over a pastorate in Leeds, England. Next door to his home was a brewery, and...