Two major problems in understanding Joseph Priestley are that he wrote so much and over such a wide area. The nineteenth-century edition of his collected works fills 25 volumes—and that leaves out the science! In discussing a man like Priestley, therefore, one cannot hope in a single lecture to do justice to the wide range of his interests or even to summarise adequately his many contributions to science. Fortunately much of the scientific work is fairly well known, for example his (...) discovery of many new gases or ‘airs’, as he preferred to call them. It might be appropriate, therefore, to try to put Priestley's pneumatic chemistry in a wider context and in particular to relate it to his career. Priestley was not only an important man of science. He was also an outspoken theologian, a literary figure and a family man, and all of these roles will have to be taken into consideration when the definitive biography is written. (shrink)