Jacob Frank's Book of the words of the Lord is one of the most extraordinary religious works of the early modern period. It was not written by Frank himself, but was a compilation of his sayings compiled by his followers, supposedly without censorship, editing or comment. Jacob Frank (1726–91), born in Podolia in what is now Ukraine, was a remarkable, charismatic and messianic figure, who emerged from the tightly-regulated religious world of eighteenth-century Polish-Lithuanian Judaism. Claiming to be the reincarnation of the seventeenth-century self-proclaimed messiah Sabbatai Zevi and the patriarch Jacob, Frank's challenge to traditional rabbinic Judaism went far beyond the Sabbatian tradition on which he drew, in particular in its radical antinomianism. Frank, who was profoundly influenced by Kabbalistic mysticism, urged his followers to reject all law and conventional morality in a desire to return to the unbounded paradise enjoyed by Adam and Eve before the Fall. The book is presented as an autobiographical account of Frank's path through life, in which he claimed to be coarse and uneducated. As Rachel Elior shows, however, his thinking was deeply rooted in the Bible and both Judaic and Christian teachings. Her detailed analysis of the book, translated and updated from a 2007 Hebrew article, is sympathetic to Frank's challenge to received norms – as many scholars, particularly Jewish scholars, have not been – and she clearly believes that his thought has something to say to a modern audience, most notably in its rejection of binary gender roles – Frank, she argues, was bisexual, and saw reality as a unity of opposites, in which God was androgynous and reality was embodied with an absence of dichotomies. She is careful, however, to distance herself from his advocacy of incest, in which fathers were urged to sleep with their daughters and brothers with their sisters; rejection of all law and all taboos can have certain dubious consequences, after all. The commentary and analysis is deeply informed, drawing on the substantial Polish and Jewish scholarship on the matter, which is treated with admirable balance and clarity. The book will be essential reading for all those interested in Frank in particular, and the Judaeo-Christian mystical tradition in general. Closely focused on the text, it does not consider, and cannot therefore shed any light on, Frank's extraordinary appeal, which brought him thousands of followers, or the bizarre course followed by the Frankists, including their extraordinary mass baptism in 1759 into the Catholic Church, not an institution known for its enthusiastic endorsement of antinomianism: within a year Frank had duly been arrested and imprisoned on a charge of heresy. Nevertheless, there is much to learn about popular attitudes to religion in the eighteenth century from a study of Frankism, and Rachel Elior has provided an indispensable guide to the thought that inspired the wider Frankist movement. It was his followers, after all, not Frank himself, who wrote all this down.