Isaac’s Fear is a wide-ranging study of a Hebrew encyclopedia of Judaism by Isaac Lampronti, a rabbi and physician from eighteenth-century Ferrara, in Italy; this is the first encyclopedia of Judaism, with entries on thought and praxis. The book’s eight chapters are previously published studies. Isaac’s Fear represents the attempt to synthesize modern science and religious tradition, a fundamental issue then and in our own day. Encyclopedia entries illuminate the society and culture of early modern Italy, its Jewish community and the intellectual life of the author and his contemporaries.