This book flows from a relationship between two scholars who do research on slavery in very different societies. Enrico Dal Lago works on the southern United States, Konstantina Katsari on ancient Rome. In 2004 they held a conference at the National University of Ireland in Galway. This is a selection of the papers. They focus on Greco-Roman and modern American slavery and are more concerned with comparison than with continuities. This means that they are dealing with the first and the most developed of what Moses Finley considered “slave societies,” societies based on slave labor and where slavery shaped politics, social structure, and cultural values. They are concerned with systems rather than with slavery in more general terms.

In their introduction, Dal Lago and Katsari lay out different approaches to comparison, focusing on Peter Kolchin's distinction between “rigorous” and “soft” comparison. The soft approach looks at a particular case, but uses comparative data to lay out possible explanations. Rigorous comparison involves the selection of two societies and examines a precisely defined theme in those societies. Only two papers use the rigorous approach. A model of this approach is the paper by the two editors examining slave management in Rome and the U.S. South. Books and articles on slave management in the two societies are surprising similar, recommending a balance between paternalism and a strict approach to work and to discipline. The experts in both societies believed in equity and a judicious balance between the carrot and the stick. The other example of the rigorous approach is a similar paper by Rafael de Bivar Marquese and Fabio Duarte Joly comparing Jesuit writing from Brazil to Greco-Roman ideology. They present an argument similar to Dal Lago and Katsari, but with the Jesuits more concerned with religious indoctrination and with the impact of ancient models on modern thinkers. The two papers are concerned with ideals rather than realities. Given any disagreements on what were just benefits or proper obligations, the masters had the ultimate sanctions in whips and chains.

The book starts with a third approach to comparison, which can be labeled global. Orlando Patterson looks at slavery throughout the world and across time, focusing on questions of gender and work. The first part of the paper is an examination of the nature of slavery, which rigorously examines various approaches to the subject. The rest of the paper uses a statistical analysis of George Peter Murdock's cross-cultural data set to explain when and where slavery will appear. The Murdock data set is very valuable, but its weakness is that its value depends of the data that went into it. The picture of each society depends as much on the language and perceptions of the individual scholar as on the differences between the societies being catalogued. It is also ahistorical. By contrast, Joseph Miller is concerned with processes of historical change over more than 5,000 years. The result is a wide-ranging paper that does not provide comparison, but does incorporate chance and recognize the particularity of different situations and the continuities in the development of slave systems. Similarly wide-ranging, but without the depth of Patterson and Miller is an paper by Olivier Pétré-Grenouilleau on exits from slavery, which skates superficially over different forms of manumission and revolt. It does not, for example, develop the ways amelioration and manumission strengthen slave systems. Also general is a paper by Stanley Engerman, which examines schemes for ending slavery with Engerman's usual precision and learning. There is also a paper by Michael Zeuske on comparisons of slave systems in the Americas, which takes as its point of departure the writing of Alexander von Humboldt in the early nineteenth century.

The other papers are all examples of Kolchin's soft approach. The best is one by Stephen Hodkinson on the agrarian relations between the Spartans and their helots, which illustrates how classicists can build a persuasive argument on very little data and can use comparison to explain how other societies dealt with whatever problem is being discussed. Hodkinson takes that limited body of data and uses examples from very extensive reading in the slavery literature to make an argument that in much of the area under Spartan rule, the helots were sharecroppers and that the system worked effectively and lasted centuries because it was able to incorporate a helot elite as intermediaries. Walter Scheidel and Tracey Rihll also use comparative data skillfully to examine problems in ancient history. Economic historians will like Scheidel's paper, which argues “that the success of chattel slavery is a function of the specific configuration of several critical variables: the character of specific economic activities, the incentive system, the normative value system of a society, and the nature of commitments required of the free population” (pp.105–06). In particular, he argues that high real wages and low slave prices were crucial in the choice of slave labor. Rihll calls into question the notion that slaves cannot be trusted with machinery. She argues that the opposite is true, that slaves were in Greco-Roman antiquity a major source of skilled labor and that skilled labor was an opportunity for slaves to earn enough to buy their freedom. They seem for that reason to have been harder workers than free persons and were probably a source of innovation.

It is not clear whether Dal Lago and Katsari imposed strict marching orders for the Galway conference, but this volume is most interesting as an exploration of the use of comparison as a tool for historical explanation. It is those authors who engage with the editors on the use of comparison that make the book valuable. It also marks Dal Lago and Katsari as scholars worth watching.