Influences: Art, Optics, and Astrology in the Italian Renaissance

By Mary Quinlan-McGrath

Today few would think of astronomy and astrology as fields related to theology. Fewer still would know that physically absorbing planetary rays was once considered to have medical and psychological effects. But this was the understanding of light radiation held by certain natural philosophers of early modern Europe, and that, argues Mary Quinlan-McGrath, was why educated people of the Renaissance commissioned artworks centered on astrological themes and practices.  Influences is the first book to reveal how important Renaissance artworks were designed to be not only beautiful but also—perhaps even primarily—functional. From the fresco cycles at Caprarola, to the Vatican’s Sala dei Pontefici, to the Villa Farnesina, these great works were commissioned to selectively capture and then transmit celestial radiation, influencing the bodies and minds of their audiences. Quinlan-McGrath examines the sophisticated logic behind these theories and practices and, along the way, sheds light on early creation theory; the relationship between astrology and natural theology; and the protochemistry, physics, and mathematics of rays. An original and intellectually stimulating study, Influences adds a new dimension to the understanding of aesthetics among Renaissance patrons and a new meaning to the seductive powers of art.  

• Language: English
• Publisher: Open Road Integrated Media
• Release date: Feb 20, 2013
• ISBN: 9780226922850

Book preview

Mary Quinlan-McGrath is professor of art history at Northern Illinois University.

The University of Chicago Press, Chicago 60637

The University of Chicago Press, Ltd., London

© 2013 by The University of Chicago

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Publication of this book has been aided by a grant from the Millard Meiss Publication

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Quinlan-McGrath, Mary

Influences : art, optics, and astrology in the Italian Renaissance / Mary Quinlan-McGrath.

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Includes bibliographical references and index.

ISBN-13: 978-0-226-92284-3 (cloth : alkaline paper)

ISBN-10: 0-226-92284-7 (cloth : alkaline paper)

ISBN-13: 978-0-226-92285-0 (e-book)

ISBN-10: 0-226-92285-5 (e-book) 1. Art, Renaissance—Italy. 2. Astronomy, Renaissance—Italy. I. Title.

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This paper meets the requirements of ANSI/NISO Z39.48-1992 (Permanence of Paper).

Influences

Art, Optics, and Astrology in the Italian Renaissance

Mary Quinlan-McGrath

The University of Chicago Press

Chicago and London

Illustration by Cesare Cesariano for Vitruvius, De architectura (Como: Gotardus de Ponte, 1521), fol. xi (verso). Courtesy of the University of Chicago Special Collections Research Center.

To MDG

CONTENTS

Preface

Introduction

1. The Study of the Heavens Is Holy: The Cosmos, the Creator, Vision, and the Soul

2. Let There Be Light: Rays in the Macrocosm

3. Celestial Rays and the Earthly World of Change

4. The Physical Nature of Vision, the Material Image, and the Soul

5. Early Modern Ecosystems: The City, the Building, the Person

6. Architectural Theory and Astrological Foundations: Three Case Studies

7. The Hidden Power in a Picture: How Celestial Rays Are Trapped in Images

8. Look, Reflect, Be Changed: The Great Astrological Vaults of the Italian Renaissance

Conclusion

Acknowledgments

Notes

Bibliography

Index

Plates

PREFACE

This text investigates why art patrons of the fiffeenth and sixteenth centuries in Italy came to believe that celestial forces could operate through their works of art and architecture. By the end of this text, I hope to persuade the reader that, given the evidence, there was a logical basis to this belief, even to the claim that the artwork affected the mind of the viewer in physical ways. This understanding gives a new meaning to the seductive power of art.

.   .   .

Any sentient person who experienced a sunburn, or anyone who lived near the sea and noticed that the tides were correlated with the motions of the Moon, had some understanding that the heavens predictably influenced the things of Earth. Ancient Greek travelers had reported that the regions of the Scythian North, where the Sun was weakest, produced people as white skinned as their snows and that the strong Sun at the equator had blackened the Ethiopians. Celestial rays flowed in, and the heavens changed the Earth in observable patterns. The predictable change of the Earth by the heavens was the subject of astrology. Over the centuries, a very sophisticated astrological discipline emerged, convincing even to the greatest astronomers, including Regiomontanus, Copernicus, Kepler, and Galileo. If the great scientists from Ptolemy through Kepler disparaged some of the details as incorrect and some of the practitioners as sloppy or unethical, the science itself was considered a reliably developing field. The macroconcepts concerning the unity and variety of the cosmos—its shared matter and shared force or energy as well as how these could be described mathematically—lay behind astrological study and still guide scientific inquiry today. Intellectual astrologers were part of this lineage.

The Italian Renaissance also saw an efflorescence of visual arts related to the heavens. In past publications, I have considered specific questions of meaning in artworks having astronomical and astrological themes. But behind these studies loom the bigger questions. What did these artworks mean in the metaphysical and physical world inhabited by patrons and their audiences? How did the precepts of natural philosophy anchor a deeper understanding of the artworks? In what ways, beyond communicating ideas, did Renaissance intellectuals consider the artworks efficacious? I will argue that the most astrologically devout believed that visual culture itself could be animated by celestial forces and that the study of light radiation linked astrology, optics, and art. When properly treated through astrological practices, urban plans, architecture, and images were thought to participate in the convergence of celestial powers and to focus the radiation of the heavens on the city as a whole, its buildings, and its residents. This combination of art and astrology might sound like a belief in magic were it not a logical consequence of the finest Aristotelian and Neoplatonic natural philosophy of the time. This logic and a sense of discovery lay behind these practices and the arts produced within this context.

In addition to examining the philosophical and scientific precepts, my work in this book also underscores a second point. We know that our experience of art is highly subjective. What we believe affects both what we see and how we perceive it. I suggest here that an understanding of urban plans, architecture, sculpture, and paintings that were believed to be infused with protective celestial powers made these works of human hands differently perceived by their original audiences. These works were considered alive in ways that we miss.

Using the ancient model of macrocosm to microcosm, I have organized the chapters from the larger concepts to the more particular. Chapter 1 treats metaphysical principles behind these beliefs. Chapters 2–4 focus on physical principles. These chapters on early science move from the simplest (the structure of the universe and its relation to the horoscope map) to the most complex (the relation between radiation, vision, and the soul). Chapter 5 explains astrological conjecture in early modern treatises on geography and then sets out the resulting understandings of the astrological relations between cities, buildings, and patrons. Chapter 6 turns to architectural treatises popular in the Renaissance that had astrological principles at their base and then considers three exemplary case studies—a city, a church, and a private residence—that demonstrate how the concepts in the geographic and architectural treatises were put into practice. Chapter 7 explains the rationale for the participation of two-dimensional artworks, especially paintings, within astrological protocol. Chapter 8 analyzes important astrological fresco cycles as efficacious astronomical images, thought to trap and transmit celestial rays, changing the viewers, or even those in the vicinity,¹ both intellectually and physically.

Briefly put, this text traces a certain understanding of light radiation—radiation that moves from the orb of the universe to the orb of the eye.

A Note on Capitalization and Terminology

There are several terms that have a common meaning to us but that had technical meanings for the natural philosophers we will be studying. I have capitalized these terms—for example, Form, Species, Qualities, Matter, and (after these are defined in their most technical sense in chapter 3) Rays—in order to remind the reader that they are not to be thought of in our sense. Matters of definition: I will often refer to a lover of the knowledge of nature, a philosopher of nature, as a scientist, a less cumbersome term. I will normally refer to what is popularly called a talisman as an astronomical image. I will use demon for a fallen angel but daemon for the term as Ficino used it.

INTRODUCTION

No lesson of psychology is perhaps more important for the historian to absorb than this multiplicity of layers, the peaceful coexistence of incompatible attitudes. There never was a primitive stage when all was magic; there never happened an evolution which wiped out the earlier phase.

E. H. GOMBRICH

In 1497, the year before he was executed, the great opponent of judicial astrology, Girolamo Savonarola, wrote with frustration that many now trusted more in astrologers than in God.¹ Although the claim was rhetorical, it is certainly true that astrological beliefs permeated the culture of Renaissance Italy from the highest levels of political and intellectual power to the lowest. A glance at recent research in this area turns up the names of Popes Julius II della Rovere, Leo X Medici, and Paul III Farnese, the intellectual leaders Marsilio Ficino and Giovanni Pontano, the brilliant mathematician and astronomer Regiomontanus, rulers of state such as the Sforza and the Este, and the entrepreneurial giant Agostino Chigi.²

From astrological formulas it was believed that one could predict the weather and related harvests or famines, foresee the advent of plagues and devise medical remedies, avoid the disasters of war, unmask rebellious citizens, and better control the daily issues of one’s life and fortunes. Condoieri set their marches by the stars, and popes convened consistories according to their rays. With such promise, and with a substructure securely grounded in state-of-the-art mathematics and astronomy, it is no wonder that astrology mesmerized the poor and the rich, the educated and the uneducated alike. Knowledge of the future has long been sought.³

Terms

We make a distinction today between astronomy, the province of cuing-edge mathematicians and physicists, and astrology, often considered the realm of a demimonde. By contrast, in the Renaissance, the terms astronomy and astrology were typically used synonymously, sometimes inversely to our meaning, and, when a distinction was made, astrology was often thought the more important of the two.⁴ The ancient scientist Ptolemy, who was both astronomer and astrologer, distinguished between the two disciplines, but most people who practiced the one also practiced the other, as did Ptolemy. Precise mathematical tracking of the heavens, part of astronomy in our sense of the term, was necessary as a technical base for the interpretive study, astrology.⁵ If one made the distinction, astrology was based on the theoretical physics and protochemistry that related the heavens and the Earth in precise ways and was credited with the application of celestial knowledge for altruistic goals. Astronomy had both the benefits and the limitations of its essential mathematical purity.⁶

While astronomy and astrology were generally used interchangeably in the fourteenth and fifteenth centuries, two other concepts should be distinguished since these had different fates in the intellectual controversies over astrology. Predicting the future required judgments or interpretations. As long as those judgments concerned macroevents such as the changes in seasons and weather patterns or the sudden disruption caused by earthquakes, volcanic eruptions, air pollution, or ensuing plagues, the validity of astrology was rarely doubted, even by its most acerbic critics.⁷ But predictions applicable to the individual seemed to threaten free will and, therefore, posed a different set of problems, both ethical and scientific.

Controversy and Astrology: Nature and Free Will

While the long history of the debates over astrology is beyond the scope of this inquiry, a couple of points that are relevant to this book as a whole might be noted. It is a commonplace in the history of astrology that the practice ran afoul of religions because predictions were perceived to interfere with free will.⁸ While this was a common complaint of religious authorities, the emphasis on free will without further contextualization can be misleading. If the case of free will were simple, it would be hard to explain why intellects and canonical saints, such as Albert the Great and Thomas Aquinas, both of whom will figure in central ways in this text, believed astrology to be a valid and even beneficial science.

When preachers inveighed against charlatans and the destruction of free will, as clerics from Augustine in the fifth century to Savonarola in the fifteenth did, it is because they had already decided against astrology for at least one larger reason. The discipline did not convincingly follow the laws of nature. If it had, it would have been understood as the Creator’s will, and that would have ended the discussion. But was that set of stars known as Leo a constellation made by God or an artificial construct of the human imagination? Were the mathematical measurements used in astrology those of nature or thirty degree limits set by human convention? The role of nature in the debate will be a central question throughout this text. In short, the controversies over free will were largely controversies over what was caused by nature and what was only imagined to be so caused.⁹ Astrological principles were ultimately subjected, we will see, to the most rigorous Aristotelian and Neoplatonic scientific scrutiny.

In this introduction, however, I would like to take just a moment to note the larger qualifiers that modify the discussion of free will and nature. First, it was understood that nature by itself did determine many things but that the human soul was still free. For reasons that will be made clear in chapter 2, the celestial bodies were considered important participants in natural generation. No one doubted then (or now) that one’s natural generation, resulting in one’s birth, had already determined many features of one’s life: one’s family, gender, social status, biological and psychological health or complexion, talents, and many other characteristics. These issues clearly limited one’s life choices, even in certain ethical ways. The choice to take someone’s life, for example, was considered ethically different for a ruler than for a peasant. Different birth temperaments were also understood to require different degrees of self-control.¹⁰ But theologians did not see these naturally determined issues as infringing on free will any more then than now.¹¹

Citing Ptolemy, Arab natural philosophers such as Abū Ma’shar, and others, the medieval scientist and cleric Roger Bacon noted that astrologers do not maintain that there is an absolute necessity in things below due to the influence of the heavens, because free will is not subject to the things of Nature.¹² In general, celestial radiation was understood to affect bodies, including human bodies, but not the immaterial rational intellect, in this period considered the site of the immortal soul. In other words, the intellectual soul was above the material determinations of nature in the hierarchy of God’s creation and should triumph over it. How one behaved when confronted with fate was always a matter of personal will. The stars inclined because of their physical influences, but this did not determine the choices one made.

Further, only the foolish would take any prediction as absolute and follow it blindly. Serious astrologers pointed to the many issues that made predictions likely approximations rather than certainties. In the case of an individual, the nature of the parents, the location of birth, and other equally important conditioning factors had to be considered when a judgment was made on a newborn.¹³ Apart from these material factors, there were methodological problems that precluded certainty. Astrological understandings were based on a correlation of historical skies with events witnessed at that time, but that same sky would not return in anyone’s lifetime. Others additionally argued that, even though astrological principles were correct, the mathematical knowledge had not yet been developed that could sufficiently measure the radiation of the heavens in a way that reliably predicted precise outcomes. Further, incompetent and sloppy practitioners often misused the celestial data in their computations. For these and similar reasons, the most educated astrologers expected astrological information to be carefully interpreted and taken seriously, but one was not to assume that it determined one’s fate.

Balanced against these concerns over free will, inexact science, and imprecise mathematics, theologians could yet see many positive features in the study of astronomy and astrology. In chapter 1, I point to ways in which the study of the heavens led early thinkers to essentially religious conclusions on the existence of a creator and the nature of the immortal soul. In addition, the beauty and order of the celestial world attracted people to the study of the heavens in what we might consider a mystical sense. The benevolence of the Sun, the majesty of the stars and planets undimmed by our light pollution, these seem to have made people feel intimately connected with the larger order—kin with the cosmos, microcosm to macrocosm. Such a beautiful order was seen as an attribute of the Creator, and, given that fact, the steady movements of the celestial bodies could be appreciated as markers of truth. Anyone who has read Dante’s Paradiso or the simple prayer of Francis of Assisi, the Canticle of the Sun, will understand this.

Further, since both ancient and early modern scientists viewed nature as purposeful and directed toward a goal, it also seemed unlikely to them that the great power of the heavens was simply beautiful or existed as a mathematical pattern.¹⁴ The Sun, the Moon, and the stars functioned—a point that was obvious for the Sun and the Moon and presumed to be the case for the other celestial bodies. Their function was part of their awesome beauty. This inevitably led to the altruistic uses of the science that were regularly considered to be astrology’s raison d’être. The Creator had intended its use for societal and personal benefits that ranged from agriculture and navigation to marital choices and medical treatments. For both mystical and moral reasons, then, the pursuit of astrology was, arguably, a theological pursuit.

In general, the problems with astrology in any theological sense were not problems with the larger natural philosophical principles of the science or even with the issue of free will. Rather, the devil was in the details.¹⁵ Some astrological practices were, at the very least, bad behavior, even if not absolutely unethical or immoral. Take the practice of predicting someone’s death. Although Scripture made it clear that the person should always be spiritually prepared for death since its time is unknown, most of the learned believed at least part of the scientific rationale for the practice of predicting the time and type of death. Because it was generally assumed by the educated that the individual’s bodily constitution, or complexion, was influenced by the inflowing of celestial rays at the moments of the person’s conception or birth, the study of astrology had become fundamental to the medical curricula.¹⁶ It follows that this inborn complexion or personal constitution—what we might today consider one’s genetic makeup—could account for biological as well as temperamental health. As such, this could affect everything from one’s length of life to the proper time to administer medicines that worked with that individual’s constitution. This logically led to astrological predictions on illnesses, life expectancy, and the circumstances that might attend one’s death.

At its most benign, this astrological practice was no more pernicious than our practice of giving a person with a life-threatening disease some sense of its likely progress. Preventive strategies or appropriate acceptance would follow. But the practice took a different turn when the prediction of death was applied to one’s enemies.¹⁷ Here, a gleeful note, or a degree of vengeful fantasy, can be detected. In addition to this ignoble schadenfreude, such prophecies could be particularly incendiary, emboldening the violent to carry out God’s work. Astrology had a bloody as well as a sublime side. For instance, astrologers claimed as validation of their science the fact that Pico della Mirandola, the outspoken opponent of judicial astrology, still died according to the time predicted by his horoscope. Others believed, however, that Pico’s sudden death was due to poisoning, mooting any natural astrological causes. Savonarola, equally scornful of the science, also died according to signs that could be seen in his birth horoscope. But his public execution according to these signs would also seem weak evidence as proof of astrology’s legitimacy. One might more readily see in this act the violent accomplishing what they took to be God’s will.¹⁸

Less dramatic problems with astrological detail resulted from the ambiguities in ancient astrological literature, which claimed to record relations between historical events and the configuration of the sky existing at the time of the event. There was no doubt about the great debt owed to two thousand years of mathematical records on the movements of the celestial bodies. But the ancient reports on the events themselves were of uneven quality and questionable validity. This literature contained internal conflicts, yet it was this ancient record on which astrologers relied for a detailed understanding of the natures of the planets, stars, decans, faces, and other astrologically potent areas of the heavens. Scholars could not easily jettison ancient witnesses derived from the cultures of Egypt, Babylon, India, Greece, and China. These revered texts often referred to yet older books that were no longer extant. Even when the learned viewed some of the information skeptically, they rarely dismissed it altogether. As the scientists saw it, they needed to work harder to understand the natural laws underlying this ancient testimony and to map the astronomical mathematics onto the witnessed accounts more accurately.

.   .   .

Given the data and the prevailing theories then available, it is easy to sympathize with diametrically opposed views on astrology in the early modern period. When two Dominicans such as Albert the Great and Girolamo Savonarola face off across the centuries, who could guarantee the winner given the available evidence? Albert saw the critique of astrology as an attack on the intellectual gifts given to people by the Creator. From his deeply learned viewpoint, ignorant naysayers were destroying a great discipline, one that was based on centuries of astronomical observations and historical testimony and that was still developing. Why would the divine have granted people the ability to track the planets and stars if not to use and improve that knowledge for worshipful and altruistic purposes? Far from inhibiting free will, in his view astrological study helped one make the best-informed life choices.¹⁹ This was using God-given intelligence.

Meanwhile, Savonarola could author a persuasive diatribe against astrology, noting, among many convincing arguments, that astrological prognostications were read subjectively, that people remember only the anomalous coincidence and quickly forget all the other erroneous predictions, and, further, that scapegoating the planets was, ultimately, immoral—it was not Mars that created wars but the greed and luxury of princes.²⁰ When this debate spilled over into the Reformation, Protestant thinkers were equally divided. Melanchthon took the approach of Albert the Great, while others echoed the arguments of Savonarola.

The learned controversy over astrology in this era is fascinating because the evidence was in many ways inconclusive. One can find the basic issues outlined in Savonarola’s small book Contra l’astrologia divinatrice. I suggest here only a glimpse of the debate’s parameters. But this must suffice, for I do not wish to distract my reader from the central questions of this book—why the learned believed in astrology and how art participated within its practices.

The great nineteenth-century historian and critic of astrology Auguste Bouché-Leclercq was quick to censure what he saw as intellectual eclecticism within astrological concepts. Certainly, one can agree that astrological theories emerged from disparate early speculations on the nature of the universe, some of which contradicted each other.²¹ By the Renaissance, the best of these authorities had been integrated. Further, perhaps we should more generously admit that the culling of what were perceived to be the best of the earlier sources is still the normal practice in many disciplines. Renaissance thinkers acknowledged that the truth had a variety of origins. Where these did not conflict, the best parts of each were extracted. Where conflict remained, interpretations were advanced to adjudicate and synthesize the conflicting evidence in a developing discipline. This is still the way knowledge grows. Jacob Burckhardt knew astrology to be pervasive in Renaissance Italy, though he thought it perverse within humanist culture.²² However, he never looked into its logic and, thus, could not understand how those whom he admired could have been duped into its practice. We have a different opportunity.

ONE

The Study of the Heavens Is Holy

The Cosmos, the Creator, Vision, and the Soul

None of the accounts now given concerning the Universe would ever have been given if men had not seen the stars or the sun or the heaven.

PLATO

Who could know heaven save by heaven’s gift and discover God save one who shares himself in the divine?

MARCUS MANILIUS

On October 14, 1573, a painter waited in Rome for an order from Cardinal Alessandro Farnese to set out for the family estate at Caprarola, about thirty miles north of the city. There, this painter would undertake the design and decoration of the villa’s main audience hall in one of the most beautiful palaces of Italy (fig. 1; plates 1–3). The visitor to this room now looks up through the oval framed ceiling, ringed by painted clouds, and into the sapphire blue (plate 1). There, the great constellations of the heavens, from the Little Bear in the north to the Altar in the south, from Canis Major to the Charioteer, charge the skies as the zodiacal constellations weave between them. All these constellations, recognizable from their personifications and myths, are yet further distinguished by the golden stars that shimmer at their points of light. Two interlopers are camouflaged among them—the single planet Jupiter and a charioteer falling from the sky (plates 2 and 3, respectively). From the upper left, Jupiter hurls his lightning bolt, striking Phaeton across the ceiling at the lower right. There Phaeton, his chariot, and his team of four white horses spin into free fall.¹

1. View of the Sala della Cosmografia, Palazzo Farnese, Caprarola, ca. 1573–75. © SEAT Pagine Gialle S.p.A.

This vault and a decorative zone connecting it with the walls feature the heavens that were related to the cardinal’s birth horoscope and, through the planet Jupiter, particularly to the date and time found in that birth chart when he was to be made a cardinal at the age of fourteen years, two months, and fifteen days (fig. 2).

The next day, a special courier arrived with the order from the cardinal, and the painter began his journey. Why had the cardinal’s painter been asked to wait? We will probably never know with certainty, but the evidence suggests that, just as condoieri, ship captains, and merchants waited for the right celestial moment to begin a campaign or commence a trip, the cardinal’s painter was asked to wait for the elected astrological time to set out.² At least we do know with certainty that important members of the Farnese family, among them this cardinal and his even more learned grandfather, Pope Paul III, were immersed in astrological precepts and practices. We also know from the correspondence concerning the delay that the cardinal was finicky about every detail of this frescoed hall. He was seeking a decoration based on sound doctrine and practice and good authors (the astrological poet Hyginus alone is named). Part of best practice for the creation of an astronomical image was the selection of the most propitious celestial rays under which to embark on the mission. This special sky was found through the construction of an election horoscope.

2. Horoscope of Cardinal Alessandro Farnese. From Luca Gaurico, Tractatus astrologicus (Venice: Curtius Troianus di Navò, 1552), fol. 36r. Courtesy of The Newberry Library, Chicago. Call no. Case B 8635.328.

In fact, this vault itself may have been understood by the cardinal as a functioning astronomical image—one that attracted, held, and then passed on celestial rays to the viewer or even to casual visitors. We will return to the cardinal’s painter at the end of this book. But it should be noted at the outset that the learned Farnese were far from alone in their devotion to astrology in early modern Italy. In later chapters, I will add to the Farnese patrons such others as the Della Rovere, the Chigi, the Sforza, and the Medici, all of whom also funded astrological works of art and architecture.

.   .   .

Today, few would think of astronomy and astrology as fields related to theology. Fewer still would consider that physically absorbing celestial rays could have been considered a spiritually beneficial exercise. But early modern scientists often drew theological and altruistic conclusions from a study of the heavens. Without this religious subtext, one tied to the scientific laws of the Creator’s natural world, it would be hard to explain why educated religious people such as the Farnese and others patronized artworks centered on astrological themes and practices.

It is symptomatic of the intimate relation between science and theology in this area that I will rely on natural philosophers such as Plato and pagan poets such as Manilius to make the theological case for astrology in this first chapter. Then I will turn to theologians to explain the scientific principles in the chapters devoted to science.³

The relations between vision, epistemology, astrology, and theology that are central to the argument of my text are all found, in nuce, within Plato’s Timaeus. In this text, four closely interrelated points are salient. (1) The study of the heavens had convinced ancient natural philosophers that there was a unified cosmos, and this suggested the work of a single creator. (2) This study had led to a corollary belief that the Creator had given people, alone among all animals, a share in the divine intelligence, this share being the immortal part of the soul or psyche. Without this sharing of the divine intelligence, people would neither have noticed the cosmic patterns nor have been able to track and understand them. (3) Vision served as the threshold for the study of the heavens. (In this chapter, we will see how the premise has a philosophical basis, and, in chapters 3–4 and 7–8, we will see the ways in which vision and the visual arts were understood to interact with the heavens in physical ways.) (4) Finally, a corollary of the previous points, the study of the heavens was itself considered spiritually beneficial. It provided insight, especially of a mathematical type, into the created universe. This, in turn, led to a marveling at the cosmic order and from that to awe and reverence for its creator. This process was considered spiritually formative for the immortal part of the soul, preparing it for its return to the Maker at the death of the body. This therapeutic aspect of celestial observation gave spiritual purpose to both the science and the art. Following the logic of the ancient philosophers and poets, it is not surprising to find that an intellectual cardinal, Pierre d’Ailly, living and working in Italy in the fifteenth century, could call astrology natural theology.⁴

In this chapter, I provide a snapshot of these four concerns, tracking a select group of ancient and early modern authors who were admired by Renaissance astrologers—Plato, Manilius, Ptolemy, Albert the Great, Roger Bacon, and Marsilio Ficino. While these four points will be acknowledged as philosophical concerns in this chapter, in subsequent chapters we will see that all four also had physical consequences. In those physical consequences, the aetherial descends to the earthy. However, both the larger metaphysical concepts and their physical corollaries grounded the belief in astrology and did so in ways in which the visual arts were understood to participate.⁵

See the Unity—a Single Maker

At an observational level, the intricately repeating patterns of the heavens and the apparently purposeful and beneficial relations of these patterns to days and nights, to the seasons, tides, climates, and geographic diversity, had led philosophers to speculate that the universe was not random and accidental but rather a purposeful, interrelated, and beautiful order. Such beauty and harmonious operation suggested the work of a single benevolent mind—a creator of that integrated whole. This observed connectedness of the cosmos was a basic understanding on which both the theory of a creator and the theory of astrology were grounded. The observations of mathematical astronomy supported the protochemical and physical connections understood to be part of astrological theory.⁶

In Plato’s Timaeus, the eponymous speaker is introduced as our best astronomer [who] has made it his special task to learn about the nature of the Universe. Timaeus then provides the probable account of the creation of the world, an account that seems to have grounded the relation between vision, astronomy-astrology, and the curative nature of the heavens for Renaissance astrologers: None of the accounts now given concerning the Universe would ever have been given if men had not seen the stars or the sun or the heaven. But as it is, the vision of day and night and of months and circling years has created the art of Number and has given us the notion of Time but also means of research into the nature of the Universe. From these we have procured Philosophy in all its range, than which no greater boon ever has come or will come, by divine bestowal unto the race of mortals.⁷ In Plato’s account, observation of the heavens and reflection on their logic lead to the development of all the intellectual disciplines, which he summarizes. First among these is mathematics, or Number. But the further mention of research into the nature of the Universe suggests pre-Socratic understandings of the elements, the proto chemistry, physics, and physiology that are featured in the Timaeus. Finally, the study of the heavens procured Philosophy in all its range as celestial observation leads to considerations of the nature of the universe, of the divine, and of the place of the person in the cosmos. This observation of and reflection on the physical, Timaeus notes, had thus led to theories of the metaphysical, Philosophy, and ultimately to the theory of a beneficent creator of this world, Plato’s Demiurge.⁸

Teachings of later Platonists, especially Plotinus (d. 270 CE), were central to theologians in the monotheistic traditions, Augustine being the most notable Christian example. Plotinus interpreted Plato’s theory of a unified cosmos in a way even more appealing to these religious traditions. He theorized that the created world was an extension of the Maker, an emanation from the One.⁹ According to this theory, a succession of entities flowed forth from the One, each becoming more material as it existed at a greater distance from its immaterial divine source. Within this hierarchical descent, where each superior level governed its successors, the stars and planets occupied an intermediary position between the One and the terrestrial world. The celestial world was the most rarified part of the material world and carried within it all the Qualities of the lower earthly entities. At the farthest remove from the One was the Earth. Though sullied by its materiality, it was still connected to the divine.

Plotinus’s emanation theory, as it was developed by late antique and early modern scientists, grew to include physical consequences, especially in relation to the physics of light rays.¹⁰ By the thirteenth century, the natural philosopher and bishop of Lincoln Robert Grosseteste, whom we will meet in later chapters, and the fifteenth-century scientist and priest Marsilio Ficino could rely on Plotinus’s understanding of Plato for a highly refined theory relating to light, universal causation, and vision that Ficino further connects to practices within astrology and the visual arts.¹¹

Turning from the philosophical to the ancient poetic tradition, these four themes found in the Timaeus are also common. The Roman poet Marcus Manilius’s Astronomica is the source for several Renaissance astrological artworks and provides a poetic parallel to the Platonic logic.¹² Appreciated by Renaissance intellectuals and art patrons alike, Manilius probably owed his popularity in this period to his theological speculation. His text is so laced with religious feeling that one forgets at times that it is a work of astrology. In book 1, Manilius asserts that the beautiful cosmic order is evidence of a divine reason and creator: "For my part I find no argument so compelling as this to show that the universe moves in obedience to a divine power and is indeed the manifestation of God, and did not come together at the dictation of chance. . . . If chance gave such a world to us, chance itself would govern it. . . .