Richard H. Popkin (1923–2005) was a pioneer in the field of Jewish studies. His numerous books and articles broke new ground in the study of Jewish-Christian relations in the early modern period and in the exploration of the impact of Jews and Judaism on philosophy and religious thought. A Sceptical Jew: Richard H. Popkin’s Private Republic of Letters brings together selections from Popkin’s private correspondence and other documents to illuminate the sources of his interests and the nature of his contributions to the fields in which he worked.