Western Civilization: Volume B: 1300 to 1815, 8th Edition
Page 50
Ancient Authors and Renaissance Artists
Whereas medieval scholars had made use of Aristotle, Galen, and Ptolemy in Latin translations to develop many of their positions in the fields of physics, medicine, and astronomy, the Renaissance humanists had mastered Greek and made available new works of Galen, Ptolemy, and Archimedes as well as Plato and the pre-Socratics. These writings made it apparent that even the unquestioned authorities of the Middle Ages, Aristotle and Galen, had been contradicted by other thinkers. The desire to discover which school of thought was correct stimulated new scientific work that sometimes led to a complete rejection of the Classical authorities.
Renaissance artists have also been credited with making an impact on scientific study. Their desire to imitate nature led them to rely on a close observation of nature. Their accurate renderings of rocks, plants, animals, and human anatomy established new standards for the study of natural phenomena. At the same time, the “scientific” study of the problems of perspective and correct anatomical proportions led to new insights. “No painter,” one Renaissance artist declared, “can paint well without a thorough knowledge of geometry.”1 Renaissance artists were frequently called on to be practicing mathematicians as well. Leonardo da Vinci devised “war machines,” and Albrecht Dü;rer made designs for the fortifications of cities.
Technological Innovations and Mathematics
Technical problems such as accurately calculating the tonnage of ships also stimulated scientific activity because they required careful observation and precise measurements. The fifteenth and sixteenth centuries witnessed a proliferation of books dedicated to machines and technology, all of which espoused the belief that innovation in techniques was necessary. The relationship between technology and the Scientific Revolution was not a simple one, however, for many technological experts did not believe in abstract or academic learning. Indeed, many of the technical innovations of the Middle Ages and the Renaissance were accomplished outside the universities by people who emphasized practical rather than theoretical knowledge. In any case, the invention of new instruments and machines, such as the telescope and the microscope, often made new scientific discoveries possible. The printing press had an indirect but crucialrole in spreading innovative ideas quickly and easily.
Mathematics, so fundamental to the scientific achievements of the sixteenth and seventeenth centuries, was promoted in the Renaissance by the rediscovery of the works of ancient mathematicians and the influence of Plato, who had emphasized the importance of mathematics in explaining the universe. While mathematics was applauded as the key to navigation, military science, and geography, the Renaissance also held the widespread belief that mathematics was the key to understanding the nature of things. According to Leonardo da Vinci, since God eternally geometrizes, nature is inherently mathematical: “Proportion is not only found in numbers and measurements but also in sounds, weights, times, positions, and in whatsoever power there may be.”2 Moreover, mathematical reasoning was seen as promoting a degree of certainty that was otherwise impossible. In the words of Leonardo da Vinci: “There is no certainty where one can neither apply any of the mathematical sciences nor any of those which are based upon the mathematical sciences.”3 Copernicus, Kepler, Galileo, and Newton were all great mathematicians who believed that the secrets of nature were written in the language of mathematics.
Renaissance Magic
Another factor in the origins of the Scientific Revolution may have been magic. Renaissance magic was the preserve of an intellectual elite from all of Europe. By the end of the sixteenth century, Hermetic magic had become fused with alchemical thought into a single intellectual framework. This tradition believed that the world was a living embodiment of divinity. Humans, who it was believed also had that spark of divinity within, could use magic, especially mathematical magic, to understand and dominate the world of nature or employ the powers of nature for beneficial purposes. Was it Hermeticism, then, that inaugurated the shift in consciousness that made the Scientific Revolution possible, since the desire to control and dominate the natural world was a crucial motivating force in the Scientific Revolution? One scholar has argued:
It is a movement of the will which really originates an intellectual movement. A new center of interest arises, surrounded by emotional excitement; the mind turns where the will has directed it and new attitudes, new discoveries follow. Behind the emergence of modern science there was a new direction of the will toward the world, its marvels, and mysterious workings, a new longing and determination to understand those workings and to operate with them.4
“This time,” the author continues, “the return to the occult [Hermetic tradition] stimulates the genuine science.”5 Scholars debate the issue, but histories of the Scientific Revolution frequently overlook the fact that the great names we associate with the revolution in cosmology— Copernicus, Kepler, Galileo, and Newton—all had a serious interest in Hermetic ideas and the fields of astrology and alchemy. The mention of these names also reminds us of one final consideration in the origins of the Scientific Revolution: it largely resulted from the work of a handful of great intellectuals.
Toward a New Heaven: A Revolution in Astronomy
* * *
FOCUS QUESTION: What did Copernicus, Kepler, Galileo, and Newton contribute to a new vision of the universe, and how did it differ from the Ptolemaic conception of the universe?
* * *
The greatest achievements in the Scientific Revolution of the sixteenth and seventeenth centuries came in the fields most dominated by the ideas of the Greeks—astronomy, mechanics, and medicine. The cosmological views of the Later Middle Ages had been built on a synthesis of the ideas of Aristotle, Ptolemy (the greatest astronomer of antiquity, who lived in the second century C.E.), and Christian theology. In the resulting Ptolemaic (tahl-uh-MAY-ik) or geocentric conception, the universe was seen as a series of concentric spheres with a fixed or motionless earth at its center. Composed of the material substances of earth, air, fire, and water, the earth was imperfect and constantly changing. The spheres that surrounded the earth were made of a crystalline, transparent substance and moved in circular orbits around the earth. Circular movement, according to Aristotle, was the most “perfect” kind of motion and hence appropriate for the “perfect” heavenly bodies thought to consist of a nonmaterial, incorruptible “quintessence.” These heavenly bodies, pure orbs of light, were embedded in the moving, concentric spheres, which in 1500 were believed to number ten. Working outward from the earth, eight spheres contained the moon, Mercury, Venus, the sun, Mars, Jupiter, Saturn, and the fixed stars. The ninth sphere imparted to the eighth sphere of the fixed stars its motion, and the tenth sphere was frequently described as the prime mover that moved itself and imparted motion to the other spheres. Beyond the tenth sphere was the Empyrean Heaven—the location of God and all the saved souls. This Christianized Ptolemaic universe, then, was finite. It had a fixed outer boundary in harmony with Christian thought and expectations. God and the saved souls were at one end of the universe, and humans were at the center. They had been given power over the earth, but their real purpose was to achieve salvation.
This conception of the universe, however, did not satisfy professional astronomers, who wished to ascertain the precise paths of the heavenly bodies across the sky. Finding that their observations did not always correspond to the accepted scheme, astronomers tried to “save appearances” by developing an elaborate system of devices. They proposed, for example, that the planetary bodies traveled on epicycles, concentric spheres within spheres, that would enable the paths of the planets to correspond more precisely to observations while adhering to Aristotle’s ideas of circular planetary movement.
Medieval Conception of the Universe. As this sixteenth-century illustration shows, the medieval cosmological view placed the earth at the center of the universe, surrounded by a series of concentric spheres. The earth was imperfect and constantly changing, whereas the heavenly bodies that sur
rounded it were perfect and incorruptible. Beyond the tenth and final sphere was heaven, where God and all the saved souls were located. (The circles read, from the center outward:
© Image Select/Art Resource, NY
Copernicus
Nicolaus Copernicus (nee-koh-LOW-uss kuh-PURR-nuhkuss) (1473–1543) had studied both mathematics and astronomy first at Krakow in his native Poland and later at the Italian universities of Bologna and Padua. Before he left Italy in 1506, he had become aware of ancient views that contradicted the Ptolemaic, earth-centered conception of the universe. Between 1506 and 1530, he completed the manuscript of his famous book, On the Revolutions of the Heavenly Spheres, but his own timidity and fear of ridicule from fellow astronomers kept him from publishing it until May 1543, shortly before his death.
Copernicus was not an accomplished observational astronomer and relied for his data on the records of his predecessors. But he was a mathematician who felt that Ptolemy’s geocentric system was too complicated and failed to accord with the observed motions of the heavenly bodies. Copernicus hoped that his heliocentric or sun-centered conception would offer a simpler and more accurate explanation.
Copernicus argued that the universe consisted of eight spheres with the sun motionless at the center and the sphere of the fixed stars at rest in the eighth sphere. The planets revolved around the sun in the order of Mercury, Venus, the earth, Mars, Jupiter, and Saturn. The moon, however, revolved around the earth. Moreover, according to Copernicus, what appeared to be the movement of the sun and the fixed stars around the earth was really explained by the daily rotation of the earth on its axis and the journey of the earth around the sun each year.
Copernicus, however, was basically conservative. He did not reject Aristotle’s principle of the existence of heavenly spheres moving in circular orbits. As a result, when he put forth the calculations to prove his new theory, he retained about half of Ptolemy’s epicycles and wound up with a system somewhat simpler than that of the Alexandrian astronomer but still extremely complicated.
Nevertheless, the shift from an earth-centered to a sun-centered system was significant and raised serious questions about Aristotle’s astronomy and physics despite Copernicus’s own adherence to Aristotle. It also seemed to create uncertainty about the human role in the universe as well as God’s location. Protestant reformers, adhering to a literal interpretation of Scripture, were the first to attack the new ideas. Martin Luther thundered against “the new astrologer who wants to prove that the earth moves and goes round… . The fool wants to turn the whole art of astronomy upside down. As Holy Scripture tells us, so did Joshua bid the sun stand still and not the earth.” Luther’s cohort at Wittenberg, Philip Melanchthon, condemned Copernicus as well:
The eyes are witness that the heavens revolve in the space of twenty-four hours. But certain men, either from the love of novelty, or to make a display of ingenuity, have concluded that the earth moves, and they maintain that neither the eighth sphere [of the fixed stars] nor the sun revolves… . Now it is a want of honesty and decency to assert such notions publicly, and the example is pernicious. It is the part of a good mind to accept the truth as revealed by God and to acquiesce in it.6
The Copernican System. The Copernican system was presented in On the Revolutions of the Heavenly Spheres, published shortly before Copernicus’s death. As shown in this illustration from the first edition of the book, Copernicus maintained that the sun was the center of the universe and that the planets, including the earth, revolved around it. Moreover, the earth rotated daily on its axis. (The circles read, from the insideout:1.Sun;2.Mercury,orbit of 80 days; 3. Venus; 4. Earth, with the moon, orbit of one year; 5. Mars, orbit of 2 years;
© Image Select/Art Resource, NY
The Catholic Church remained silent for the time being; it did not denounce Copernicus until the work of Galileo appeared. The denunciation came at a time when an increasing number of astronomers were being attracted to Copernicus’s ideas.
Brahe
Copernicus did not have a great impact immediately, but doubts about the Ptolemaic system were growing. The next step in destroying the geocentric conception and supporting the Copernican system was taken by Johannes Kepler. It has been argued, however, that Kepler’s work would not have occurred without the material provided by Tycho Brahe (TY-koh BRAH).
A Danish nobleman, Tycho Brahe (1546–1601) was granted possession of an island near Copenhagen by King Frederick II. On it, Brahe built the elaborate Uraniborg Castle, which he outfitted with a library, observatories, and instruments he had designed for more precise astronomical observations. For twenty years, Brahe patiently concentrated on compiling a detailed record of his observations of the positions and movements of the stars and planets, a series of observations described as the most accurate up to that time. This body of data led him to reject the Aristotelian-Ptolemaic system, but at the same time he was unable to accept Copernicus’s suggestion that the earth actually moved. Brahe’s last years were spent in Prague as imperial mathematician to Emperor Rudolf II, who took a keen interest in astronomy, astrology, and the Hermetic tradition. While he was in Prague, Brahe took on an assistant by the name of Johannes Kepler.
Kepler
Johannes Kepler (1571–1630) had been destined by his parents for a career as a Lutheran minister. While studying theology at the university at Tübingen (TOO-bing-un), however, he fell under the influence of Michael Mästlin (MEST-lin), Germany’s best-known astronomer, and spent much time pursuing his real interests, mathematics and astronomy. He abandoned theology and became a teacher of mathematics and astronomy at Graz in Austria.
Kepler’s work illustrates well the narrow line that often separated magic and science in the early Scientific Revolution. An avid astrologer, Kepler possessed a keen interest in Hermetic mathematical magic. In a book written in 1596, he elaborated on his theory that the universe was constructed on the basis of geometric figures, such as the pyramid and the cube. Believing that the harmony of the human soul (a divine attribute) was mirrored in the numerical relationships existing between the planets, he focused much of his attention on discovering the “music of the spheres.” Kepler was also a brilliant mathematician and astronomer and, after Brahe’s death, succeeded him as imperial mathematician to Rudolf II. There he gained possession of Brahe’s detailed astronomical data and, using them, arrived at his three laws of planetary motion. These laws may have confirmed Kepler’s interest in the “music of the spheres,” but more important, they confirmed Copernicus’s heliocentric theory while modifying it in some ways. Above all, they drove another nail into the coffin of the Aristotelian-Ptolemaic system.
* * *
On the Revolutions of the Heavenly Spheres
Nicolaus Copernicus began a revolution in astronomy when he argued that the sun and not the earth was at the center of the universe. Expecting controversy and scorn, Copernicus hesitated to publish the work in which he put forth his heliocentric theory. He finally relented, however, and managed to see a copy of it just before he died.
Nicolaus Copernicus, On the Revolutions of the Heavenly Spheres
For a long time, then, I reflected on this confusion in the astronomical traditions concerning the derivation of the motions of the universe’s spheres. I began to be annoyed that the movements of the world machine, created for our sake by the best and most systematic Artisan of all [God], were not understood with greater certainty by the philosophers, who otherwise examined so precisely the most insignificant trifles of this world. For this reason I undertook the task of rereading the works of all the philosophers which I could obtain to learn whether anyone had ever proposed other motions of the universe’s spheres than those expounded by the teachers of astronomy in the schools. And in fact first I found in Cicero that Hicetas supposed the earth to move. Later I also discovered in Plutarch that certain others were of this opinion. I have decided to set his words down here, so that they may be available to everybody:
Some think
that the earth remains at rest. But Philolaus the Pythagorean believes that, like the sun and moon, it revolves around the fire in an oblique circle. Heraclides of Pontus and Ecphantus the Pythagorean make the earth move, not in a progressive motion, but like a wheel in a rotation from the west to east about its own center.
Therefore, having obtained the opportunity from these sources, I too began to consider the mobility of the earth. And even though the idea seemed absurd, nevertheless I knew that others before me had been granted the freedom to imagine any circles whatever for the purpose of explaining the heavenly phenomena. Hence I thought that I too would be readily permitted to ascertain whether explanations sounder than those of my predecessors could be found for the revolution of the celestial spheres on the assumption of some motion of the earth.
Having thus assumed the motions which I ascribe to the earth later on in the volume, by long and intense study I finally found that if the motions of the other planets are correlated with the orbiting of the earth, and are computed for the revolution of each planet, not only do their phenomena follow therefrom but also the order and size of all the planets and spheres, and heaven itself is so linked together that in no portion of it can anything be shifted without disrupting the remaining parts and the universe as a whole… .