This is the first book to present a carefully chosen and annotated selection of the unpublished writings and correspondence of the English logician John Venn (1834-1923). Today remembered mainly as the inventor of the famous diagram that bears his name, Venn was an important figure of nineteenth-century Cambridge, where he worked alongside leading thinkers, such as Henry Sidgwick and Alfred Marshall, on the development of the Moral Sciences Tripos. Venn published three influential textbooks on logic, contributed some dozen articles to the then newly-established journalMind, of which he became...