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22.10.10 Hamburger, Color in Cusanus

22.10.10 Hamburger, Color in Cusanus

In his erudite study of Cusa’s thought, Jeffrey Hamburger focuses primarily on the diagrammatic illustrations to Cusa’s De coniecturis (“On Surmises”). Forty-two full page color plates accompany his text. The captions for each plate, along with short descriptions lifted from the main text, are placed mostly on the facing pages, which are otherwise blank. This extravagance of space adds to the overall impression of the luxuriousness of this short hardcover book, almost half of which comprises the material of the color plates. These range in subject from an eleventh-century cosmological diagram of Bede’s eighth century treatise, De Temporum Ratione (“The Reckoning of Time”) to near contemporary illustrations such as one of Heymeric of Camp’s mid fifteenth-century diagrams of Sigillum aeternitatis (“The Seal of Eternity”), a copy of which Cusa owned.

Born in 1401 to a rich merchant in Germany, Nicholas of Cusa (Cusanus) advanced to become a papal advisor and cardinal. He broadened his interests in theology and canon law to include reflections on cosmological and mathematical modes of knowledge. Cusa’s goal was to inquire into the ways in which the nature of God and the cosmos can be known. The first 5 chapters deal primarily with geometrical diagrams, considered by Cusa as the most efficacious means by which the mind can envisage the cosmos and ascend to the knowledge of God.

For Cusa, as Hamburger states in “Thinking through Diagrams” (chapter 1), “mathematical ideas” help the mind to unfold “a conceptual universe that parallels and forms an image of God’s unfolding of the created world” (24). This mode of thought puts a Christian spin on Platonic and Pythagorean traditions. According to Hamburger, what Cusa did was to add color to diagrams. He goes on to discuss the symbolism of such geometric figures as the triangle, the circle, the sphere, and their various permutations. All these, as Hamburger quotes Cusa as saying, are “present in the potency of an infinite line” (33). Hamburger imagines Cusa contemplating the tiled floors of a painting by Jan van Eyck. One can’t help but think of M. C. Escher’s step-by-step search for infinity in his geometric transformations.

Cusa’s approach assumes an ordered, rational universe that can best be known by following a rational process of tracing diagrams. This movement involves three types of perceptions: corporeal, intellectual, and transcendental. By interpreting a geometrical diagram, the mind comes closest to God’s act of creation because “both engage in the act of measuring, and God is the ultimate geometer” (46). This is supported by Wisdom 11:21; to which could be added Isa. 40:12 and Prov. 8:27. Although not discussed by Hamburger, these potent biblical passages have been immortalized in such visual adaptations as the famous frontispiece to the mid thirteenth-century Bible moralisée (Vienna, ONB 2554) in which the cross-nimbed deity bends over a large compass or divider that describes the center and circumference of the universe he is creating. [1] Such images have a long artistic legacy, including William Blake’s 1821-1827 etching depicting the Ancient of Days measuring out the world with dividers extending from his fingers, [2] and Carle Hessay’s 1974 painting of the Ancient Mariner of the Space Age who is shown as a geometer designing a new world. [3] All these conceive of the act of creation as a rational process using the principles of geometry.

In “Color as Vector” (chapter 2), Hamburger explores, for example, Heymeric’s diagram (mentioned above), to which color was added, although not in Cusa’s copy. In the Middle Ages, color was associated “with the body and senses,” while line was associated “with the mind and idea” (48). Heymeric’s diagram, then, expresses not only “the nature of the Trinity, but also of its workings in the world” (49). Color is “the first rung on the anagogical ladder leading up to the invisible things of God,” but yet God’s wisdom remains veiled in these vestiges of his presence, constituting Heymeric’s idea of the “seal” (50).

Using the metaphor of the mirror, in “Cusan Speculation” (chapter 3), Hamburger discusses the relationship between the perceiving subject and the subject of representation. Along with a treatise on icons, Cusa sent a panel of the Holy Face to the monks of Tegernsee so that they could have a “sensible” figure. The viewer moves thereby to see “with inner eyes the truth which is pointed to by the painting” in an “exchange of gazes” (Hamburger quoting Cusa, 58). Humans can participate “only to a limited degree” (59). Nevertheless, as Hamburger points out, Cusa never directly addresses “art-making” (56). For Cusa, “the process of viewing an image serves exclusively as a metaphor for the process by which the human subject comes to know God, who by his nature lies beyond the reach of sight” so that, paradoxically, God “can only be known through a process of unknowing or, in his words, docta ignorantia” (59).

Man’s sense of wonder is “akin to a spark that sets the mind in motion” with the senses providing the “kindling for the fire of the intellect” (62). In “Diagrams in Action” (chapter 4), Hamburger rightly observes that medieval diagrams “demanded a form of diagrammatic literacy” (64). He points out that diagrams pervaded the seven liberal arts in the medieval curriculum: the quadrivium consisting of arithmetic, geometry, music, and astronomy, and the trivium consisting of grammar, logic, and rhetoric. Yet in none “did color, let alone light a critical role,” but Cusa’s diagrams “offered something new” (68).

In “Color in De coniecturis” (chapter 5), Hamburger reflects on Cusa’s identification of God as light, and colour as a contraction of it. To simplify, “color complements line” and “provides the very embodiment of materiality” (72). Cusa was interested in optical effects for “what they mean, but also of how they were perceived” (78). Further, gradations of light and shade were important elements in his conceptions of diagrams. For present purposes, perhaps it is helpful to consider one of his diagrams for De coniecturis. Picture two interpenetrating pyramids or triangles, with the one starting out as light and the other as dark. In the middle zone (the median world) where they interpenetrate there is gray, but at either end there is some light in the darkness and some darkness in the light. This serves as a metaphor for the “linked processes of knowing and well as their fundamental incommensurability” (87). Or, to put it another way, as Hamburger quotes Cusa, “God’s being in the world is nothing other than the world’s being in God,” illustrating how God participates in history (88). In other diagrams, interpenetrating spheres are visualized in a similar fashion.

This anticipates the final and most interesting chapter, at least for art historians, “An Orb in the Hand of God” (chapter 6). Because of the focus on spheres, Hamburger leads readers to see with new eyes the orbs held by the deity not only in the paintings he has chosen for interpretive purposes, but by extension, in other paintings not included in this book. He points out the importance of the light glancing off the orb, for example, as an “opening to a higher reality” (105). Further, reflected light can lead not only to looking beyond, but also inward to self-reflection.

It must be a disappointment, therefore, that for whatever technical reasons, the actual color of the plates is flat, blurry, and lacking in vibrancy. Commendably, it is printed on a holzfreien (wood-free) paper. Hamburger’s main text is sharp enough. To give but one example, Plate 42 showing facing pages of Christ in Majesty with Titulus in the Hitda Codex is so unclear that one cannot read the words of the Titulus that the “visible visualization gives form to that invisible truth” (108). This is a pity because Hamburger calls attention not only to the words, but also to the pigments that convey the message of the inscribed Titulus: gold and white for divinity and red for humanity. [4]

While this book might more accurately be titled Diagrams in Cusa, Hamburger does his best to tease out relevant passages in Cusa dealing with color. The complexities and depth of Hamburger’s learned disquisition are barely covered here. This book is suitable for academic libraries and advanced readers in matters of theology and mathematics, especially in relation to art history, but it is stimulating also for a wider audience who might find themselves inadvertently drawing diagrams. The subject of Cusa’s own questioning search for cosmic truth is newly current with the recently released images from the James Webb Space Telescope which reach back almost to the dawn of time.



1. Gott als Schöpfer der Welt (“God as Creator of the World”), Bible moralisée, Codex Vindobonensis 2554, Vienna, Öesterreichische Nationalbibliothek, fol. 1v, mid-thirteenth century; see online at:

2. See the image of “The Ancient of Days” in the Fitzwilliam Museum in Cambridge at:; also in the exhibition at the Tate Gallery in London: For Blake, however, this concept of a rational order is not necessarily a positive one; rather, it signifies a “reductive, scientific approach,” as seen by his monoprint of Newton with a pair of dividers tracing a diagram; see the Tate:

3. See the painting by Carle Hessay, The Ancient Mariner of the Space Age, 1974 at:

4. Contrast the color differences between Plate 42 and an online facsimile version of “Christ in Majesty with Titulus”, Hitda Codex, Cologne, Darmstadt, Hessische Universitätes-und Landesbibliothek, HS 1640, fols. 6v-7r, c. 1000: