Giles E. M. Gasper

A three-dimensional color space from the 13th century.

We present a new commentary on Robert Grossetestes De colore, a short treatise that dates from the early 13th century, in which Grosseteste constructs a linguistic combinatorial account of color. In contrast to other commentaries (e.g., Kuehni & Schwarz, Color Ordered: A Survey of Color Order Systems from Antiquity to the Present, 2007, p. 36), we argue that the color space described by Grosseteste is explicitly three-dimensional. We seek the appropriate translation of Grossetestes key terms, making reference both to Grossetestes other works and the broader intellectual context of the 13th century, and to modern color spaces.

Color-coordinate system from a 13th-century account of rainbows

We present a new analysis of Robert Grossetestes account of color in his treatise De iride (On the Rainbow), dating from the early 13th century. The work explores color within the 3D framework set out in Grossetestes De colore [see J. Opt. Soc. Am. A29, A346 (2012)], but now links the axes of variation to observable properties of rainbows. We combine a modern understanding of the physics of rainbows and of human color perception to resolve the linguistic ambiguities of the medieval text and to interpret Grossetestes key terms.

A medieval multiverse?: Mathematical modelling of the thirteenth century universe of Robert Grosseteste

In his treatise on light, written about 1225, Robert Grosseteste describes a cosmological model in which the universe is created in a big-bang-like explosion and subsequent condensation. He postulates that the fundamental coupling of light and matter gives rises to the material body of the entire cosmos. Expansion is arrested when matter reaches a minimum density and subsequent emission of light from the outer region leads to compression and rarefaction of the inner bodily mass so as to create nine celestial spheres, with an imperfect residual core. In this paper, we reformulate the Latin description in terms of a modern mathematical model, teasing out consequences implicit in the text, but which the author would not have had the tools to explore. The equations which describe the coupling of light and matter are solved numerically, subjected to initial conditions and critical criteria consistent with the text. Formation of a universe with a non-infinite number of perfected spheres is extremely sensitive to the initial conditions, the intensity of the light and the transparency of these spheres. In this ‘medieval multiverse’, only a small range of opacity and initial density profiles leads to a stable universe with nine perfected spheres. As in current cosmological thinking, the existence of Grosseteste’s universe relies on a very special combination of fundamental parameters.

‘A doctor in the house’? The context for Anselm of Canterbury’s interest in medicine with reference to a probable case of malaria

This paper discusses the nature of Anselm of Canterbury’s interest in medicine, an interest that has been noticed in passing before but never properly explored. The evidence comes mainly from the 1070s and 1080s when he was prior of the abbey of Bec in Normandy. His interest consistently arose from the duties and responsibilities of community life. It is in part a textual interest revealed by requests for medical books from Canterbury. It is also related to a dynamic web of monastic relations between Canterbury and Bec bound together by friendship. Anselm’s letters reveal a deep concern for the physical well-being of members of his community and his practical medical care is noted. A letter detailing symptoms of two monks sent to him from Canterbury exemplifies this. One of the cases is highly suggestive of malaria. This not only demonstrates the clarity of Anselm’s observations, but also is significant evidence in its own right for the history of malaria in Britain between the Anglo-Saxon period and the fourteenth century. Anselm’s interest in medicine lies on the cusp between theological thought and practical action. It also offers wider perspectives on the nature of monastic medical care and the theme of friendship in the eleventh and twelfth centuries.

Bow-shaped caustics from conical prisms: a 13th-century account of rainbow formation from Robert Grosseteste's De iride.

The rainbow has been the subject of discussion across a variety of historical periods and cultures, and numerous optical explanations have been suggested. Here, we further explore the scientific treatise De iride [On the Rainbow] written by Robert Grosseteste in the 13th century. Attempting to account for the shape of the rainbow, Grosseteste bases his explanation on the optical properties of transparent cones, which he claims can give rise to arc-shaped projections through refraction. By stating that atmospheric phenomena are reducible to the geometric optics of a conical prism, the De iride lays out a coherent and testable hypothesis. Through both physical experiment and physics-based simulation, we present a novel characterization of cone-light interactions, demonstrating that transparent cones do indeed give rise to bow-shaped caustics-a nonintuitive phenomenon that suggests Grossetestes theory of the rainbow is likely to have been grounded in observation.

Money and its use in the thought and experience of Anselm, archbishop of Canterbury (1093–1109)

This article explores aspects of a broader question: what money meant to the inhabitants of north-western Europe in the late eleventh and early twelfth century, evidence for its use, and how it was conceptualised and discussed. The existence of money is well attested in the archaeological record. A monestised economy, central to the working of royal and comital courts, as well as mercantile, urban and rural communities, is also well documented in the archival record, perhaps most famously for Anglo-Saxon England. However, for all of the tangible numismatic material and evidence of sophistication in the management of coin production, surprisingly little attention has been paid to investigating how money was actually used, and, specifically, how the use of money in this formative period was understood, articulated and expressed. This article adopts an explicitly inter-disciplinary approach to the subject to interrogate a range of source material not previously examined in this context. It focuses on the sources associated with Anselm, archbishop of Canterbury (1093–1109), some 475 letters and the contemporary Life and complementary historical work written by his close companion Eadmer of Canterbury. The discussion opens up further dimensions of Anselms life and thought, as well as offering a detailed insight into an individuals experience with and thinking about money in the later eleventh and early twelfth century.

Unity and Symmetry in the De Luce of Robert Grosseteste

We examine Robert Grosseteste’s treatise on light, De Luce, from the perspective of symmetry within his unified view of natural phenomena. Spherical symmetry in his expanding-universe cosmological model is crucial to its integration into Aristotle’s vision of a series of concentric celestial spheres under the operation of a single prime mover. While posing difficulties by the increasing intensity of the lumen emitted by the perfected spheres, the spherical symmetry enables him to provide an explanation of vertical motion and change more generally. In the final paragraph of the treatise, we find that Grosseteste uses numbers, based on underlying physical symmetries, to explain the presence of nine perfected celestial spheres and one imperfect sub-lunar sphere, containing the sub-spheres of the four elements. The concept of underlying symmetry is still used in modern physics—we present an example in the context of twentieth-century particle physics. The rationale for, and the connection to the remainder of the treatise becomes evident when numerical simulations are performed using equations derived directly from Grosseteste’s text. His model explains the formation of the perfected celestial spheres, but there is no route by which it can predict their number. Completion of the description of the Universe can only be achieved by appeal to simplicity and symmetry.

The Fulfillment of Science: Nature, Creation and Man in the Hexaemeron of Robert Grosseteste

Robert Grosseteste’s commentary on the six days of creation, the Hexaemeron, is one of his most extensive and detailed theological works. Composed during his time as bishop of Lincoln, it draws on earlier lectures, notably those on Genesis, and his scientific treatises. In the Hexaemeron Grosseteste provides a powerful definition of theology, arguing that it should not be identified as a science, but in the course of this definition deploying Aristotelian definitions with great skill. The Hexaemeron displays to the full the depth of range of Grosseteste’s reading, and provides, in its commentary on creation, the fulfillment of his earlier work, placing investigation of natural phenomena in the service of exegesis. This paper will explore pertinent themes for Grosseteste’s use of his earlier writing, and the implications of their subsequent interpretation. Nature, Creation and their interpretation by human reason allow Grosseteste wide scope for commentary, all grounded in the proper subject of theology, the unifying work of Christ.

Envy, Jealousy, and the Boundaries of Orthodoxy: Anselm of Canterbury and the Genesis of the Proslogion

Anselm of Canterbury’s Proslogion is one of the most celebrated of medieval treatises. This discussion seeks to examine more closely the circumstances in which the Proslogion was conceived and took shape. In particular it analyses the account of the composition of the treatise by Anselm’s later companion Eadmer of Canterbury. Eadmer’s account has never been examined in detail before, and the story he relates of the loss (probably by theft) and destruction of drafts of the treatise is intriguing and instructive. The investigation questions the environment in which Anselm’s treatise was composed, and suggests a degree of factional political life within his monastery at Bec. The legacy of Lanfranc at Bec, the nexus of links between Canterbury and Bec in the last quarter of the eleventh century, and Anselm’s own defensiveness about his intellectual achievements are central aspects to the discussion.

Anselm and the "Articella"

Sometime between 1070 and 1077, Anselm, then prior of the monastery of Bee in Normandy, wrote to his friend Maurice, a former Bee monk residing at Christ Church, Canterbury, and asked him to seek out copies of various texts, including Bedes De temporibus and the Regula of St. Dunstan — presumably the Regularis concordia, the platform-document of the English Benedictine reform of the tenth century.1 Shortly thereafter, Anselm wrote again to Maurice, indicating that another text had been added to his desid-