American Scientist

The First Copernican: Georg Joachim Rheticus and the Rise of the Copernican Revolution. Dennis Danielson. viii + 264 pp. Walker and Company, 2006. $25.95.

The 16th-century astronomer and mathematician Georg Joachim Rheticus confronts 21st-century readers with an enigma. A humanist steeped in Latin and Greek, Rheticus proclaimed himself a lover of the classics. In 1541, when he offered a lecture course on astronomy at the University of Wittenberg, he described Ptolemy's second-century handbook of astronomy, the Almagest, as "by far the most beautiful among works of human hands." Rheticus had used equally flattering language to describe Ptolemy in 1540 in the book for which he is chiefly remembered—his Narratio Prima, in which he offered the European public its first detailed report on the heliocentric planetary theory of Copernicus, which he enthusiastically espoused. Even in this manifesto he praised Ptolemy—whose geocentric astronomy Copernicus rejected—as "the divine parent of astronomy." Indeed, Rheticus noted that Copernicus had set out his own work in imitation of Ptolemy's.

For all his love of traditional scholarly pursuits, Rheticus was a thoroughly modern, unbookish figure. He loved to travel, preferred direct observation of the skies to reading old texts about them and eagerly collaborated with the printers who were transforming the fabric of learned life. In his later years, he rejected all of Greek planetary theory, including the work of Ptolemy, in favor of what he called an "astronomy without hypotheses." Moreover, in his second career, as a medical man, he rejected the ancient theories of Galen and accepted the radical new iatrochemistry—alchemical medicine—of Paracelsus. Which, one wonders, was the true Rheticus—the humanist who wrote eloquent Latin or the innovator who chose modern theories over ancient ones even when doing so made his personal situation risky?

In The First Copernican, Dennis Danielson brings learning, admiration and precise scholarship to the task of writing the first popular biography of this puzzling figure. His excellent book reconstructs Rheticus's life in crisp, well-documented detail. Danielson follows this picaresque scientist on his many journeys, vividly sketching the many intellectual circles that he joined. A first, short trip took the talented young man from Feldkirch, near Lindau, where he was born in 1514, to Zurich, where he studied with noted scholars such as Conrad Gesner. A second, longer foray brought him north to the new intellectual heartland of Lutheranism: He finished his education at the University of Wittenberg—the academy of Martin Luther and Philipp Melanchthon. In 1536, at the age of 22, Rheticus became a professor of mathematics there, and further travels in the area took him to Nuremberg, where he met Johannes Petreius, a Nuremberg publisher.

In the spring of 1539, finally, Rheticus set out on the journey that would transform both his life and the larger history of science. Three weeks of hard travel took him far to the east and north, to the town of Frauenburg, near the Baltic cities of Danzig and Königsberg. There, he had heard, an aged cathedral canon named Nicolaus Copernicus was doing work of great importance in astronomy.

Danielson describes the encounter between the two men with precision and empathy. An expert on the history of astronomy, he lucidly lays out the course of Copernicus's career and explains his project for the renovation of astronomy. An insightful biographer, Danielson also makes clear that Rheticus was looking for more than new data and models. Rheticus's own father had been publicly beheaded as a swindler, and as Danielson shows, Rheticus spent much of his life looking for older mentors and father figures. One of them, the scholar and medical man Achilles Pirmin Gasser, put him on the road to Wittenberg. Another, Copernicus's bishop, Tiedemann Giese, took an instant liking to Rheticus and helped persuade Copernicus to cooperate with him.

Copernicus, however, offered far richer intellectual sustenance than any of Rheticus's other surrogate fathers. When he saw that Rheticus understood and accepted his plan to transform planetary theory, he eagerly began to work with the young man. They carried out observations together, so intensively that Rheticus's health suffered. Meanwhile Rheticus worked his way gradually through all the details of the new astronomy. The old man had long hesitated to make his theories public. But when this ideal reader materialized, Copernicus allowed him to write and publish a First Accountof these theories. And when that elegant little book met with favorable responses, the two men began to prepare Copernicus's own work for the press. In 1541, as Rheticus reluctantly made his way back to Wittenberg, he carried with him a manuscript of Copernicus's De Revolutionibus, which Petreius would publish two years later.

The appearance of this book, in turn, set off a slow but certain revolution in mathematics and the physical sciences. Readers across Europe filled its margins with comments and began testing its arguments—a process that Owen Gingerich has charted in magnificent, microscopic detail in The Book Nobody Read. Danielson empathetically recreates the vital collaboration that made all this possible, a relationship both intellectual and emotional.

Eventually Rheticus moved from Wittenberg to a higher-paid and more prestigious job at the University of Leipzig. In 1551 he published a major mathematical work, the first six-function trigonometrical tables to appear in print. Yet his later life after 1543, although still full of travel and activity, was in many ways anticlimactic. In order to forestall censorship, the theologian Andreas Osiander took it upon himself to equip Copernicus's book—against the author's will—with an anonymous preface that described it as a pure hypothesis. Rheticus fumed, and he crossed out the preface in the copies of the book that came his way. But even when Giese, a bishop, formally complained, the Nuremberg city council held Petreius blameless, and nothing came of plans for a new edition that would reveal that Copernicus had been sure he had discovered the truth.

Tormented by financial troubles and accused of sexually assaulting a student, Rheticus left Leipzig for Prague and a new career in Paracelsian medicine. His massive planned work on trigonometry remained incomplete when he died in 1574. It was brought out after his death, in imperfect form, by a loyal pupil, Valentin Otto, who found in Rheticus the sort of mentor Rheticus himself had so often sought.

Danielson's thoughtful, well-written book portrays Rheticus as a talented mathematician and astronomer, but one who proved most successful, in the end, as an intermediary and a publicist. A skillful middleman, he brilliantly used the connections he had secured and the networks he had woven to bring Copernicus's work to the world and to advocate the new in every area from printing and cartography to astronomy. Yet Rheticus's story has a deeper level, too, one that Danielson does not quite convey. The young Rheticus, as Danielson shows, both praised Ptolemy and called for his overthrow. The older Rheticus, as Danielson mentions in passing, denounced Greek astronomy as a mass of useless theories. He insisted that the obelisk he had built in Krakow, with help from a patron, had enabled him to rebuild the science on a new foundation of observations. Danielson describes Rheticus's praise of Ptolemy as "lip service" and has little to say about the obelisk.

In fact, Rheticus was quite sincere in noting that Copernicus built on foundations Ptolemy had laid. The Almagest and the De Revolutionibus, as Otto Neugebauer and Noel M. Swerdlow have taught us, are far more alike than different in structure and method. When the older Rheticus called for the abandonment of Ptolemy, he did so in order to reconstruct a still older and purer science, that of the ancient Near East. "The Egyptians," he explained, had built the first obelisks, which they called "nature's interpreters." Copernicus's planetary theory did not abandon Ptolemy but reconfigured him—as more than one of Copernicus's later readers complained. Rheticus's new astronomy, in turn, abandoned Ptolemy only for what he saw as a still older way of establishing "the laws of this heavenly kingdom." The passionate advocate of the new was still captivated by the Renaissance myth of antiquity. Like so many early modern thinkers, from Vesalius and Copernicus to Kepler and Newton, Rheticus sought new truths both in the realm of empirical observation and in antiquity, and saw no contradiction in doing so.

Although Danielson misses this central paradox—which a writer of his gifts could have explored even in a treatment meant for general readers—he has written an excellent scientific biography: His elegant, well-illustrated book brings back to life a lost world of 16th-century scholars and their ways. More important, it is a model attempt to connect a protagonist's scientific work with his emotional and personal life, without engaging in exaggeration or bathos. And it makes clear exactly why, as Danielson notes at the start, "No Rheticus, No Copernicus." This strange man, about whom Johannes Kepler and others liked to tell lurid stories, played a crucial role in bringing Copernicus's dangerous idea to a European public that would accept it only after decades of censorship and debate.