Joseph von Sonnenfels (1733–1817), a leading figure of the Viennese Enlightenment in the age of Maria Theresa and Francis II/I and a “Man without Prejudice,” is the focus of an extensive thesis written by Simon Karstens, a scholar in Trier. Nearly all introductory overviews on the Austrian Enlightenment will mention the wide range of activities and writings of the self-satisfied Sonnenfels as a relentless fighter against torture, but to date there has been no biographical overview that brings together his life, his sphere of action, and his finely woven network of contacts. Sonnenfels may be seen either as a theorist or as an administrator, either as a reputable scientist or as an unscrupulous pamphleteer—it is very difficult to classify this restless spirit properly. Sonnenfels is considered a controversial figure within the Enlightenment: some scholars stress more the idea of his being a Jewish convert, others point out that Sonnenfels belongs to a Viennese Catholic milieu. Sonnenfels is categorized furthermore as an Illuminist and fellow-Mason or as a kind of aggressive spider spinning its bureaucratic web. Considering these problems, Karstens's goal was less to write a conventional biography that would line up the Jewish background in Mikulov/Nikolsburg (Moravia) and his academic career and more to show the life of Sonnenfels as a “sum of social interactions” (5).

The author wisely divided his subject into several chronological parts in order to tell his story in an orderly fashion: Sonnenfels started his career as a soldier and court servant (till 1763) before he was appointed professor of police (Policey) and economic affairs (till 1791), but Sonnenfels was also a highly productive writer. Another phase of his life shows him as collaborator on reform projects that also meant less productivity as an author because of a lack of time. With Francis II's rise to power, the “theorist” Sonnenfels concentrated on stronger engagement with government reforms. In the end his opus magnum was left incomplete: the so-called Political Codex collecting all laws of the Habsburg monarchy. A great deal of source material has been lost as a result of a fire at the Palace of Justice in 1927. Historians have long viewed the selfish Sonnenfels as only an antitorture advisor; Karstens clearly shows this was not the case. Besides an enormous number of brochures, the book's main sources are the records of the Viennese Haus-, Hof-, and Staatsarchiv (for example, documents of the Imperial Commission on Education).

The activities of Joseph von Sonnenfels were comprehensive and often enough the reader of the book receives the impression of an “enlightened” jack-of-all-trades. So multilayered was his career and so varied were his critics. The book documents his many fields of activity: Sonnenfels as academic teacher (69–175), as censor (177–231), as member of secret societies (Freemason, Illuminist) (233–80), and finally as the mighty state reformer (281–461). Pugnacity, a highly visible presence in the many brochures produced during Joseph II's reign, and a very effective network allowed Sonnenfels to set aside his pen and made him a wily political actor who never shied away from conflict, no matter the power of the opponent. Notable opponents included Gottfried van Swieten (Imperial Commission on Education) and Franz von Zeiller (Imperial Commission in Hofkommission in Legislative Matters). His was a central voice of enlightened Vienna, opining on Hanswurst-comedies and the significance of German-speaking and non-German-speaking theater, the abolition of torture and the suspension of the death penalty, the reform of police forces in Vienna, the role of the police within the Habsburg monarchy (secret police system versus welfare police), the reform of the education system and the preparation of the German Civil Code. Starting in 1780, Sonnenfels also took on the Herculean task of collecting all the legislation within the Habsburg monarchy. As the third pillar alongside the German Civil Code and Criminal Law, the “Political Codex” aimed to provide a basis for further legislation. The Commission presided over by Sonnenfels had to screen an estimated 1.4 million documents in order to get a survey of “norms,” and nearly one-tenth of the documents would have to be copied! The death of Sonnenfels in the year 1818 meant a “sudden” end to this enormously ambitious project.

A large success of the present book is the sober assessment of the life and wide-ranging work of Sonnenfels founded securely on archival research. As it turns out, not a few of the reforms attributed to him were not actually his work; additionally, Karstens unearthed several of Sonnenfels's responsibilities that were not previously known (for example, Sonnenfels was responsible for urban lighting of Vienna).

Karstens clearly demonstrates that Sonnenfels was not acting alone, a voice calling in the wilderness. He was not a lonesome reformer but a highly effective networker often moving faster than other “enlightened” authors. Sonnenfels increasingly held the position of chief conductor in his network of noble and bourgeois men and among a widespread circle of disciples. He could initiate or at least co-design reforms based on his proximity to the emperor, by using the brochures, or by pressuring officials. The influence Sonnenfels had “depended strongly on the action of other players and the interaction he had with these players” (469). Reading Karstens's book will not give the reader a biographical picture of Sonnenfels. We cannot compare him directly with other restless exponents of European Enlightenment, and we will not get an impression of how Sonnenfels was seen by his contemporaries and by posterity (for example, in the nineteenth century), but we do get a detailed, profound insight into his field of activities.