Medical Astrology: Science, Art, and Influence in early-modern Europe

Between Heaven and Earth

Explore: The Ecliptic and the Zodiac Belt | The Celestial and Terrestrial Spheres | The Order of the Cosmos

Astrologer casting a horoscope in his study. From: Utriusque Cosmi (1617–1621). Click the image for more information. 

A common refrain among early-modern physicians—from the Nuremberg humanist Hartmann Schedel (1440–1514) to the English physician Richard Saunders (1613–1692)—was that anyone ignorant of astrology was unqualified to be called a physician. Not all physicians necessarily shared this view. By the end of the fifteenth century, the use of astrology in medicine was a topic of ongoing debate with advocates and adversaries on either side. Both sides, however, found common ground in the general idea of celestial influence. That celestial movements influenced certain terrestrial events—like weather, temperatures, and tides—was a widely admitted proposition, though the nature of this influence was hotly debated. Both respected and reviled, professional and popular, early-modern medical astrology boasts a complex, multidimensional history that is brought to life by its imagery. Although some of this imagery is self-evident, much of it is not. To unpack the layers of meaning in these sources, this exhibition examines the language and theories associated with this practice in Europe between the fifteenth and seventeenth centuries.

Regiomontanus (Right) listens to Claudius Ptolemy (left) read from the Almagest. Click on the images for more information.

The Ecliptic and the Zodiac Belt

The concept of the ecliptic is of paramount importance for medical astrology. The word ecliptic refers to the plane of the Earth’s orbit around the Sun. In a geocentric model of the universe, this definition is simply inverted: the ecliptic conversely refers to the Sun’s apparent orbit around the Earth. From the Latin ecliptica, and the Greek ekliptikos, the ecliptic is so-called because solar and lunar eclipses can only happen when the Moon crosses this plane.

The images at right further clarify this definition. A typical, early-modern representation of the ecliptic is seen in the first image, which comes from a fifteenth-century reprint of De Sphaera mundi (1491) by Johannes de Sacrobosco or John of Holywood (ca.1195–1256). Here, the ecliptic is represented as a narrow black line at the center of a larger diagonal band, which likewise represents the plane of the Sun’s apparent orbit around the Earth. The celestial significance of this band becomes clearer in the second image—the frontispiece to The Epitome of Ptolemy (1496) by Johannes Müller von Königsberg (1436–1476), otherwise known as Johannes Regiomontanus. This band represents the slanted pathway the Sun appears to trace against the background of the stars—from the perspective of Earth—as it travels between the Tropics of Cancer and Capricorn. Clearly identified in Regiomontanus’s image, the Tropics of Cancer and Capricorn are two great circles of the celestial sphere that lie approximately 23.5° north and south of the celestial equator. These great circles mark the northern- and southern-most points of the ecliptic and were so-named for the constellations of Cancer and Capricorn. Accordingly, the pictorial symbols populating this band signify twelve of the constellations lining the course of the ecliptic—a portion of which are pictured in the image below. Notice that these stellar figures extend both above and below the ecliptic’s narrow black line. This extension is represented by the aforementioned “band,” which is properly known as the Zodiac Belt. Reaching roughly 8–9° of celestial latitude north and south of the ecliptic, the Zodiac Belt designates the broader pathway through which the Moon and the rest of the visible Planets appear to travel over the course of their respective orbits.

The Zodiac Belt is the basis for The Twelve Signs of the Zodiac in early-modern medical astrology, though the two are not identical. Notice, in the image below, that the zodiacal constellations do not occupy equal proportions of the ecliptic. The size disparity between the figure for Virgo, at left, and the adjacent image of Libra (the Scales), for example, reflects the celestial reality of these stars: Virgo is significantly larger than the rest of the constellations. By contrast, the 360-degree Zodiac Belt in the images above is divided equally among the twelve symbols. These symbols, therefore, represent The Twelve Signs of the Zodiac as opposed to the twelve constellations.

Detail of the Planisphere Volvelle from the Astronomicum Caesareum (1540). Click the image for full view and more information. 

The Celestial and Terrestrial Spheres

 

Celestial Sphere with Ecliptic and Zodiac Belt. From: Margarita Philosophica (1503). Click the image for more information.

Celestial Globe (ca.1522). Image Courtesy of the Yale Center for British Art. Click the image for more information. 

Terrestrial Globe (ca.1522). Image Courtesy of the Yale Center for British Art. Click the image for more information.

 

 

Celestial Sphere with Ecliptic and Zodiac Belt. From: De Sphaera mundi (1490). Click the image for more information.

Celestial Sphere with Constellations. From: Astronomiæ Instauratæ Mechanica (1598). Click the image for more information.

Celestial and Terrestrial Spheres. From: Cosmographia (1564). Click the image for more information. 

The images in the gallery above illustrate the Celestial and Terrestrial Spheres—two crucial concepts for early-modern medical astrology. These terms point to a geocentric model of the universe formulated in antiquity by Plato (d.348/47 BCE), Aristotle (384–322 BCE), Claudius Ptolemy (ca.100–170 CE), and others. In this cosmological system, the Earth was both conceptually and physically interconnected with the heavens, which were thought to encircle it. Although shown here as independent orbs, both the heavens and Earth were imagined as a collection of nesting spheres, with the shape of the terrestrial spheres reflecting the shape of the celestial spheres, and vice-versa. The sequence of globes seen above illustrate this formal continuity between the two realms, as well as the iconographic features that distinguish them when pictured in globe form. The pair of painted objects in the upper register—i.e., the so-called “Brixen Globes” from the Paul Mellon Collection at the Yale Center for British Art—convey this distinction with color: the golden globe at right represents the terrestrial spheres, while the dark-toned globe at center represents the celestial spheres. The representation of landmasses versus constellations is another key distinction, though the two often look quite similar. Drawing the clearest distinction between the two globes are the ecliptic and Zodiac Belt. These were the exclusive attributes of the celestial spheres, as the diagrams below further reveal.

The Order of the Cosmos

The images below present the Celestial and Terrestrial Spheres in cross section. Picturing three-dimensional shapes in two dimensions, these diagrams clarify the interconnection between the two spheres, as well as the multiple layers associated with each. They show the order of the cosmos as a collection of nesting, non-intersecting orbits with Earth at the center. Together, these concentric spherical cross sections form a veritable Jacob’s Ladder, connecting the Earth to the heavens that surround it. The terrestrial spheres, at center, are four in number. They represent the physical composition of the universe and its elemental hierarchy. Proceeding from center to periphery, this hierarchy reflects the decreasing density of the elements and begins with the densest of the four, Earth. In three of the images below, Earth is shown as a cultivated townscape. It is followed by Water—indicated by wave-like squiggles as well as fish—and Air, which is represented by a cloud-like meander pattern. The final terrestrial sphere is Fire, the lightest of the elements, is represented by flames.

De Sphaera mundi (1491). Click the images for more information.

Ein newer Kalender Von allerley Artznei durch alles him[m]liche Gestirn (1540).

Cosmographia (1564)

Himels Lauffs (1564) 

Ptolemy (left) uses a quadrant to observe the Moon and stars guided by Astronomia (right), an allegory for astronomy. From: Margarita Philosophica (1503). Click the image for more information.  

The “rungs” of the celestial spheres commence after Fire. Defining each of the celestial spheres is a symbol or glyph representing one of The Seven Planets. Although the images in the top register assume familiarity with these symbols, those in the bottom register label them clearly. Closest to the terrestrial spheres is the Moon [☽] followed by Mercury [☿], Venus [♀], the Sun [☉], Mars [♂], Jupiter [♃], and Saturn [♄]. This is the order of the Planets as seen from Earth, though popular publications of the period typically explained this order in reverse. Beginning with Saturn, the traditional planetary sequence was instead as follows: Saturn [♄], Jupiter [♃], Mars [♂], The Sun [☉], Venus [♀], Mercury [☿], and the Moon [☽]. Saturn was consistently characterized as the “first and highest” planet. It was regarded as the limit of the visible world and, in the diagrams above, marks the threshold between the planetary spheres and the outer starry sphere or Firmament. Populated with zodiacal symbols, this sphere was home to the astrological Zodiac’s namesake constellations. It is also the two-dimensional counterpart to the Zodiac Belt featured on the three-dimensional globes above. The outermost sphere—pictured only in the diagram at lower left—was the Primum Mobile or “first moved.” This outermost sphere moved from East to West, making one full revolution within a 24-hour period. Causing the inner, planetary spheres to rotate in turn, the Primum Mobile was regarded as the “prime mover” or driving force behind time and temporal change within the celestial and terrestrial spheres. As subsequent pages show, timing was of paramount importance for early-modern medical astrology.

Click the images for more information.

The above-outlined model of the cosmos underwent significant change during the period surveyed in this exhibition. A key figure in this change was the mathematician and astronomer Nicolas Copernicus (1473–1543). Drawing on the heliocentric theories of Regiomontanus, who, in turn, revived earlier solar schemes from antiquity, Copernicus prompted a shift in long-standing conceptions of the cosmos with his book De revolutionibus orbium coelestium (On the Revolutions of the Celestial Spheres). Issued prior to his death in 1543, Copernicus’ publication—so the story goes—toppled Ptolemy’s geocentric model of the universe with a proven heliocentric one, thus launching the so-called Copernican Revolution. The imagery from this period, however, tells a slightly different story. The images, at left, come from a text commonly known as the Mysterium Cosmographicum or “The Cosmographic Mystery” by Johannes Kepler (1571–1630). Published in 1596—i.e., half a century after Copernicus’s De revolutionibus—Kepler’s celestial diagrams modestly update, rather than overthrow, earlier models. In the first image, Kepler reimagined Ptolemy’s nesting spheres separated by the five platonic solids: a cube, tetrahedron, dodecahedron, icosahedron, and octahedron. The second image, however, simply adapts the order of the concentric spheres from the Ptolemaic model to reflect a heliocentric system. Kepler’s real innovation came later, between 1609 and 1619, with his Laws of Planetary Motion, which reimagined the structure of the universe with elliptical as opposed to concentric circular orbits.

Image Courtesy of Beinecke Rare Book & Manuscript Library. Click the image for more information.

Works Cited on this Page
Barnes, Robin Bruce. Astrology and Reformation. Oxford; New York: Oxford University Press, 2016.
Carey, Hilary M. “Astrological Medicine and the Medieval English Folded Almanac.” Social History of Medicine 17, No. 3 (2004): 345–363.
Cooper, Glen M. “Approaches to the Critical Days in Late Medieval Renaissance Thinkers.” Early Science and Medicine 18, No. 6 (2013): 536–65.