1 To begin with this book is full of surprises — and they are mainly good ones. Historians and ethnologists can learn a great deal about interdisciplinary research. And art historians will recognize that there is more to talk about than style (if they do not read the first 28 pages too critically).

2 The title The Art of Medieval Technology does not divulge very much about the contents of the book — even though the subtitle is Images of Noah the Shipbuilder. In the first two chapters Unger tries to outline the complicated connections between art and technology. He outlines the interconnections between church history, art history and the history of technology and thus develops his method of research. When the sources of shipbuilding are considered with the art historical sources, the result should be that "all this evidence marshalled together should support the hypothesis that artists did illustrate technology, that despite their goals they showed Noah building ships as they were built at the time the artist worked." But Unger's real goal is not only to verify this hypothesis. Above all he wants to prove, with this example, that works of art can be used as contemporary sources for the history of technology — of course with due caution. How often one heeds that caution is important in using works of art as a source. However historians can rarely restrain themselves, and they proceed to regard paintings and even medieval seals as if they were documentary photographs. And here is the greatest surprise — Unger has succeeded in shedding light on the historical conditions for a medieval work of art using the example of Noah. He describes the theological questions and interpretations concerning the construction and appearance of the ark with astounding precision. He recognizes and explains the influence of this ecclesiastical problem on the artists who illustrated the story of Noah and the Ark. At the same time, he uses the shipbuilding history of Europe in the Middle Ages to document that the artists used their own environment as a model for the presentation of the technical details, the tools and the organization of work. To those who read chapters three to nine systematically and with concentration (and that is what the book demands), Unger reveals fascinating insights into a section of European shipbuilding history. And he does it with a remarkable knowledge of literature and source material.

3 As I see it, Unger has proved his hypothesis. He has proved that works of art can be used as a source for the history of technology. At the same time he has shown the interdisciplinary efforts that are required to do this. In addition the author has documented, though unintentionally perhaps, the many questions that remain unanswered. Nevertheless this is a good outcome of Unger's investigation as he has not presented us with final research results. His book has finally started a discussion between historians and art historians that has long been necessary.

4 With Unger's work in view and with the intention to open this discussion, we must ask: How certain can we be that artists present reality (or a part of it) and are not led by their fantasies? How certain can historians be when they contend that artists had events (shipbuilding) or objects (tools) in front of them while they worked?

5 The answers are hidden among the details — as in Unger's book. The author expresses doubts about the presentation of Noah sitting while working with an axe (illustration 20, thirteenth-century Oxford Psalter). I consider it more important that Unger ignored that the frame saw shown in the same illustration is technically incorrect. The twisted cord to provide the tension is in the wrong place. An art historian would have concluded that the artist had never seen a saw or had not understood its mechanics. But it is probably the case that the artist's model was too small or inexact. Artists have often made similar mistakes when illustrating ships using other artistic works as a model, especially if they have neither seen a ship nor understood anything about them. Such mistakes may not reduce the artistic quality of a work; however, the value of the piece as a source for the history of technology sinks considerably. This is where the question of artistic style takes on considerable importance. This book examines pictures over a period of about 1300 years. The pictures are all illustrations of only one story — Noah's Ark — but they belong to different periods of style and various regions. These different styles and regions alter the thematic statement of the pictures. Unger did not deal with this problem. This is unfortunate as it blunts the methodology that he took great pains to set out in the first chapters.

6 Another flaw, from the point of view of art historians, is that the technical specifications to the pictures illustrated are missing. It is important to know how large a work of art is, whether it was intended for private use (as a psalter) or if it was accessible to the public (as the mosaics in San Marco). From this information it is possible to make deductions about the commission, the artistic intention and the social conditions of the viewer.

7 These critical comments are not intended to prevent the readers of this review from reading the book. I consider The Art of Medieval Technology: Images of Noah the Shipbuilder a very important contribution to material history and it should provide an incentive for intensive discussion.