University of Cracow. Nicholas Copernicus was born in Torun in the far north of Poland in 1473. With the support of his uncle, a prominent member of the Catholic Church, Copernicus was able to attend the University of Cracow, Poland, from 1491 to 1496, where he became interested in astronomy. Cracow was among the leading north European universities, and Copernicus would have been exposed to the latest methods and controversies within astronomy and natural philosophy there. By the late fifteenth century, astronomy was suffering from a lack of precision—the mathematical models and techniques for predicting planetary alignments were out of date—as well as a fundamental disagreement about the proper foundations and purposes of the field. The mathematical astronomy developed in the second century C.E. by Ptolemy was technically sophisticated and worked reasonably well when used with high-quality, recent observations but violated some of the basic principles of Aristotle’s philosophy, which demanded that the Moon, Sun, and five planets (Mercury, Venus, Mars, Jupiter, and Saturn) be carried around the stationary Earth on orbs, or spheres.
Entering the Fray. Aristotle’s treatises taught that the celestial world was perfect, where nothing changed or decayed. The only kind of physical motion appropriate to this region was one that did not change. The only such motion is produced by a sphere’s rotating in place at a constant speed—ever moving, but endlessly and change-lessly repeating the same movement. According to this view, the cosmos was constructed of a complex system of concentric spheres, each moved by a kind of intelligence that sought to emulate the motion of the outermost sphere, which was moved by the prime mover. Cosmologists from Eudoxus (fourth century B.C.E.) down through the ages retained this ideal of an astronomy based on homocentric spheres, but no mathematical model was constructed on this basis that could make acceptable predictions. By the late Renaissance, two distinct approaches existed: that of Ptolemy, whose mathematical approach was workable, if not philosophically acceptable, and that of Averroes, an Arabic commentator on Aristotle’s philosophy and an ardent opponent of Ptolemy’s approach. During this time Copernicus began to study astronomy.
Bologna. While Copernicus was at Cracow, his uncle was appointed bishop of Warmia (northern Poland), and Nicholas was made a canon of the cathedral of Frauenburg. A canon was a salaried member of the church and usually expected to function as an administrator and serve as a juror in the church court. To prepare Copernicus for this career, the church permitted him to use his salary to further his education in canon law (church law), and he left Cracow for northern Italy, where he enrolled at the University of Bologna in 1496. At Bologna, Copernicus neglected his legal studies and continued to study astronomy while also becoming interested in medicine. The two sciences were connected by astrology, which was necessary to determine the kind, and timing, of treatment appropriate to a particular patient. At Bologna, Copernicus would have found himself in the thick of controversy over Averroes’s interpretations of Aristotle, which opposed not only mathematical astronomy, but also the Christian teaching on the immortality of the soul. Thus, theology, astronomy, and physical cosmology intersected in arguments about the nature of the soul, the celestial intelligences that moved the planets, and how they so moved them.
Padua. Copernicus left Bologna without a degree in 1501, and after briefly returning to Poland, studied medicine at Padua (Italy), one of the foremost centers of Aristotelian philosophy in the sixteenth century and the scene of arguments between the Averroists and the Thomists (adherents to St. Thomas Aquinas’s version of Aristotelian theory) over the mortality of the soul. The Averroists interpreted Aristotle strictly where he taught that the human soul was a material form and therefore dissolved when the body decayed, an idea that was condemned by the Catholic Church in 1512. Copernicus stayed at Padua for two years, only to take his doctorate in law at the University of Ferrara, another northern Italian school.
Startling Theory. Having completed his education, Copernicus returned to Frauenburg, where he served as a secretary to his uncle, the bishop, and practiced medicine, astronomy, and engineering. In 1513 he built an observation tower, where he set up instruments for observing the relative positions of the celestial bodies. The following year he circulated a six-page manuscript treatise that first detailed his novel theory that the Sun was the real center of the cosmos, with the Earth just another planet revolving about it in an orb.
Realist Tradition. Despite a later interpretation that Copernicus intended his new, helocentric model merely as a mathematical device to enable greater precision to correct the Christian calendar, it is now clear that Copernicus was working within a realist tradition, as were all other parties to the Averroist-Ptolemaist controversy during the late fifteenth and sixteenth centuries. Realists are concerned to put forth hypotheses about the world that reflect physical reality rather than merely convenient instruments for discovery and calculation. This situation explains not only Copernicus’s later reasoning for why objects would not fall off a moving Earth and other answers to critics of heliocentrism, but also his low profile—he did not sign his name to the 1514 treatise and he only reluctantly committed his ideas to print more than a quarter of a century later.
Historical Impact. In 1539 a German Lutheran student who had come to Frauenburg to learn more about Copernicus’s ideas drafted the Narratio prima (First Report) of Copernican astronomy, which was printed and circulated the following year. Copernicus completed the full version of this theory, De revolutionibus orbium coelestium (On the Revolutions of the Celestial Orbs), which was a chapter-by-chapter answer to Ptolemy’s Almagest, including the mathematical means of calculating planetary positions, and published it in 1543, the year that he died. However, Andreas Osiander, who was overseeing the printing, surreptitiously added an anonymous statement on the back side of the title page indicating that the hypotheses discussed in the book were not to be construed as statements about the reality of the cosmos. No doubt Osiander was aware that heliocentrism would be controversial, inasmuch as it ran counter to literal interpretations of the Bible, and sought to cushion its reception by the subterfuge. People familiar with Copernicus and his work were not fooled by the preface, but it did serve to confuse historians of science in the nineteenth and early twentieth centuries, who misunderstood its historical impact.
Thomas Kuhn, The Copernican Revolution: Planetary Astronomy in the Development of Western Thought (Cambridge, Mass.: Harvard University Press, 1957).
Edward Rosen, Copernicus and His Successors (London & Rio Grande: Hambledon Press, 1995).
Robert Westman, ed., The Copernican Achievement (Berkeley: University of California Press, 1975).