Saul Levi Morteira, ‘Spinoza's rabbi’, was a prominent figure in seventeenth-century Jewish culture. After spending his youth in Venice, where he was a student of Leon Modena, he moved to Amsterdam in 1616, when he escorted the body of his patron, the physician Elijah Montalto, from Paris to burial in the Netherlands. Morteira served as a rabbi in Amsterdam until his death in 1660, and the success of the yeshiva that he established and ran in the Dutch city was immortalised by a famous contemporary poet, Miguel de Barrios. One of his duties as a rabbi was to encourage the practice of halachic Judaism among the Amsterdam-based descendants of Spanish and Portuguese conversos. This was no easy task, because many ex-conversos had left Christianity without completely returning to the Jewish Law. Furthermore, the ex-conversos of Iberian heritage, having survived inquisitorial Spain and Portugal, were united by an air of socio-religious superiority, which distinguished them from the other Jews of Amsterdam. The difficulties that Morteira met in his attempts at fully ‘rejudaizing’ the ex-conversos are reflected in his treatise Obstaculos y opoçiçiones contra la religion xptiana [sic] en Amsterdam. Morteira's Obstaculos y opoçiçiones (arguments, in Gregory Kaplan's translation) is written in the form of a dialogue between a learned ex-converso of Iberian descent, who has returned to open Judaism in Amsterdam, and a young Portuguese converso who has unsuccessfully tried to join the Society of Jesus. The only textual witness to this treatise is a manuscript copy made in 1712 and held at the Ets Haim Library of the Portuguese Synagogue in Amsterdam. Gregory Kaplan has now offered us an accurate and elegant English translation of this dialogue, complemented by an extensive apparatus of notes and an excellent introductory essay. Kaplan's introduction is valuable for several reasons. He details the history of the manuscript and gives a comprehensive account of Morteira's life, cultural background and activities in the context of the complex socio-cultural environment of Amsterdam's Jewish community. Moreover, Kaplan provides a critical analysis of Morteira's text, focusing on its main influences, sources and themes: he points out the impact of Spanish Golden Age theatre and literature – Lazarillo de Tormes above all – on Morteira's Arguments; he identifies the different biblical sources of this book, including, among others, the Ferrara Bible; and he calls attention to the role of eschatology and converso discourse in Morteira's efforts at rejudaization. Last but not least, he examines Morteira's controversial relationship with Spinoza. Briefly, Kaplan's English edition of Morteira's Obstaculos y opoçiçiones sheds new light on this author's thought and erudition. This book also makes a significant contribution to a better understanding of the life of early modern Jewish communities, particularly but not exclusively in Amsterdam, against the background of the socio-cultural relations, and of the tensions, between different components of early modern Jewry.