ABSTRACT
I begin with three objects, all made of stone and all at one time or another viewed as straddling the boundary between art and nature. The first is a cameo of probably Hellenistic origins depicting two helmeted figures in profile 2 (Figure 1), in all probability the onyx described by the thirteenth-century natural philosopher Albertus Magnus, which he had once seen at the shrine of the Three Kings in Cologne. After ascertaining that the image was made of stone rather than glass, Albertus concluded “that this picture was made naturally and not artificially,” adding that “[m]any others like this are found.” 3 No modem eye, however untutored in the techniques of cameo carving or late classical motifs, could mistake this piece for a work of nature rather than of art. Not only the intricacy of the craftmanship but also the content of the image marks it for us immediately and indelibly as made by human hands. How could Albertus have thought otherwise? It will not do to dismiss Albertus as credulous or ignorant. Although he knew little about gem cutting, he knew enough about techniques of incising, engraving, embossing, and carving stones to discuss how similar images might be made artificially. Like Pliny, he warned the unwary against forged natural curiosities of this kind. 4 Moreover, it is not primarily on grounds of what we know about how cameos are made that we base our conviction that the Ptolemy cameo is artificial rather than natural. Nor was Albertus’s judgment to the contrary unique: throughout the late Middle Ages and well into the seventeenth century, European scholars classified what seem to us to be unmistakably artifacts, such as Etruscan vases, as natural objects. 5 Why and when did the boundary between the natural and the artificial shift so dramatically? “Natural?”—“Ptolemy” Cameo, Hellenistic or Roman. Courtesy of Kunsthistorisches Museum, Vienna. https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780203699942/c5bce2d9-ed10-4e1a-8263-1d3f75974b2f/content/ch9-page233-1_B.jpg" xmlns:xlink="https://www.w3.org/1999/xlink"/>
