The Centinela contra Judíos, published first in 1674 and reedited several times until the middle of the eighteenth century, was one of most passionate works against the Jews and their converso descendants in seventeenth-century Spain. François Soyer has translated it into English and, at the same time, has produced an interesting and detailed study of Torrejoncillo's work, a contextualisation of the debate about society, culture and religion in early modern Spain, and an inquiry into the reasons for the success of Centinela and its distribution across the Spanish empire and within Spanish culture until nineteenth century. The book is divided in two parts. In the first Soyer attempts to clarify the ‘Jewish problem’ in Spain, the relationship between religion and ‘sangre’, the story and impact of the Centinela, and how it became one of the fundamental discourses in ‘antisemitic’ propaganda and pedagogy. A translation and commentary on the Centinela constitute the second part of the book. The author interprets Torrejoncillo's book as one of the supreme examples of antisemitism in early modern Spain, although he knows that this term may be vehemently debated. Soyer adopts Langmuir's thesis which argues that ‘antisemitism’ had its roots in the Middle Ages and developed in the early modern period. During this time, and especially in the fourteenth and fifteenth centuries, Christian animosity toward the Jews and an image of the Jew as a religious opponent of the truth and a demonic agent was established. As far as Spain is concerned, Soyer affirms that the Centinela may be considered as the key to the spread of a pejorative image of the Jew/converso, portrayed as a serious social, political and religious danger.

Soyer therefore stresses that this book may only be interpreted correctly when it is placed in its historical context. Its exaggerated portrait of the Jew/converso was painted at the end of an era, an era when the ‘Jewish problem’, purity-of-the-blood, and its statutes began to lose social validity. Precisely because these issues were beginning to become obsolete, Torrejoncillo tried to stir up public opinion through an easy text which could be widely distributed. In addition he gathered together, and synthesised, all Spanish and Portuguese antisemitic literature, he devised a passionate defence of the rigid social separation of New and Old Christians, the Inquisition, and purity-of--the-blood, and he even proposed the expulsion of New Christians. Soyer's work is also of a great interest for its handling of a relatively unknown fact: how, in the eighteenth century – according to Dominguez-Ortiz's ideas – Jews changed into fabulous characters, about whom grew legends.