Renaissance science and the boundaries of knowledge

The phrase “scientific revolution” is a nineteenth-century coinage, but the thing it was coined to describe is a real and identifiable feature of European life in the period between Peurbach’s Theoricae novae planetarum of 1454 and Galileo’s Dialogue Concerning the Two Chief World Systems of 1632. The science of the long sixteenth century was neither medieval nor modern; it was the science of a generation of scholars and physicians who believed themselves to be recovering the geometry of Archimedes, the astronomy of Ptolemy, the botany of Theophrastus, and the medicine of Galen, and who were in fact the first generation to treat those classical authorities as objects of criticism rather than of obedience. To understand what the period did is to understand the period’s boundaries — the boundary between Aristotelian natural philosophy and the new mathematical physics, the boundary between Galenic medicine and the new anatomy, the boundary between the Ptolemaic cosmos and the heliocentric one — and to understand the period’s historiography is to see why those boundaries are not where they once were.

The inheritance of the late medieval university

The “scientific revolution” did not begin in a vacuum. The natural philosophy taught in the universities of Bologna, Padua, Paris, Oxford, and Heidelberg in the late fourteenth and early fifteenth centuries was, in its technical achievements and in its institutional stability, a major cultural inheritance. The Oxford Calculators of the 1320s and 1330s — Thomas Bradwardine, William Heytesbury, Richard Kilvington, John Dumbleton — had worked out a kinematics of uniformly accelerated motion that depended, for the first time in Latin physics, on a clear distinction between speed, distance, and time. The Parisian terminists of the late fourteenth century — John Buridan, Nicole Oresme, Albert of Saxony — had developed a sophisticated theory of impetus as an alternative to Aristotelian antiperistasis, and a sophisticated mathematical language for the description of ratios. Buridan had used the impetus theory to propose that the heavens could be propelled by an impetus imparted at the Creation, and to free the cosmology of the primum mobile from the need for an unbroken chain of intelligent movers. Oresme had, in a famous passage of his Le Livre du ciel et du monde (c. 1377), proposed a model in which the Earth rotated on its axis daily and the heavens were at rest.

That none of these developments produced a Copernican revolution in the early fifteenth century is one of the most interesting historical problems in the historiography of the period. Edward Grant’s work on the Parisian terminists and David C. Lindberg’s Theories of Vision from al-Kindi to Kepler (1976) and The Beginnings of Western Science (1992) have shown how rich the late medieval inheritance was, and have made the older accounts of the “scientific revolution” as a sudden break with the medieval increasingly difficult to sustain. What changed in the fifteenth and sixteenth centuries was not the existence of mathematical and empirical traditions, but the cultural standing of those traditions: the way in which the recovered texts of the Greek mathematicians and the empirical methods of the humanist physicians were deployed to judge the Aristotelian and Galenic systems of the universities.

The new astronomy: from Peurbach to Copernicus

The first decisive shift was in the astronomy. The Ptolemaic system of the Almagest of the second century had reached the Latin West in the twelfth-century translations from the Arabic made in Toledo, Sicily, and Constantinople, and it had been the basic astronomical textbook of the late medieval university. The Almagest was, however, a difficult book to teach, and the early fifteenth century produced a series of works that were meant to make it more accessible. Georg von Peuerbach (1423–1461), the Viennese humanist and astronomer, wrote the Theoricae novae planetarum (1454, printed in Milan in 1472), a more tractable summary of the Ptolemaic planetary theory; his student Johannes Regiomontanus (1436–1476), the most formidable astronomer of the century, completed the Epitome of the Almagest (Venice, 1496) that Peurbach had left unfinished. The Epitome was a Latin paraphrase of the Almagest in nine books, worked from the Greek rather than from the Arabic, and it became the most important astronomical textbook of the next hundred years. Regiomontanus also built the astronomical observatory at Nuremberg, with the patronage of the patrician humanist Bernard Walther, and was the first director of the Alphonsine Library at the court of Matthias Corvinus in Buda; his Tabulae directionum of 1467 and his Ephernerides of 1474 were the working instruments of the next generation of navigators.

The next decisive shift was Nicolaus Copernicus’s De revolutionibus orbium coelestium (Nuremberg, 1543), the heliocentric system that set the Earth in rotation on its axis and in revolution around the sun. Copernicus (1473–1543), a Polish canon of the cathedral of Frombork (Frauenburg) on the Baltic, had studied at Cracow and at Bologna and Padua between 1496 and 1503, and had read the Epitome of Regiomontanus in the early years of the sixteenth century. The De revolutionibus was not, in the conventional sense, a “new” astronomy: it kept the Ptolemaic epicycles and eccentrics, the Ptolemaic mathematical apparatus, and the Ptolemaic cosmology of crystalline spheres. The novelty, the Ramon Llull moment of the new astronomy, was the relocation of the sun at the centre of the system and the rotation of the Earth. The system was, in Owen Gingerich’s phrase (The Book Nobody Read, 2004), a “well-tended garden” that was read by a small number of mathematically trained astronomers in the next century; its impact, the long, slow displacement of the Aristotelian cosmology, was a much later and a much more complicated matter.

The technical confirmation of the heliocentric system was the work of the next two generations. Tycho Brahe’s Astronomiae instauratae progymnasmata (Prague, 1602) provided the empirical data — the parallax of the comets of 1577 and 1580, the new star of 1572, the long observational series at the Uraniborg observatory on the island of Hven — on which the system could be tested. Johannes Kepler’s Astronomia nova (Prague, 1609) and Harmonices mundi libri V (Linz, 1619) gave the system the new mathematical form (the three laws of planetary motion) by which it would survive. Galileo Galilei (1564–1642), the Tuscan mathematician who had been appointed to the chair of mathematics at Padua in 1592, gave it the empirical confirmation — the telescopic moons of Jupiter (1610), the phases of Venus (1610), the mountains of the moon (1610), the Sunspot Letters (1613) — that the Aristotelian cosmology could not accommodate. The trial of 1633 in the Dominican convent of Santa Maria sopra Minerva in Rome, in which the seventy-year-old Galileo was made to abjure the Copernican doctrine, was the most dramatic of the long series of confrontations between the new astronomy and the theological and philosophical establishment. Rivka Feldhay and Mario Biagioli have, in their recent work on Galileo and Padua, shown how deeply the confrontation was embedded in the politics of the patronage of science in the early modern state.

The new anatomy: from Mondino to Vesalius

The same generation produced the new anatomy. Mondino de’ Liuzzi’s Anathomia of 1316, written in the small university town of Bologna and based on direct human dissection in the anatomia publica, had been the standard textbook of the medieval medical school for two hundred years; it kept the Galenic anatomy of the De usu partium and the De anatomicis administrationibus and used human dissection primarily as a way of confirming Galen. Mondino’s book was the great late medieval anatomical work; the new anatomy of the sixteenth century was a deliberate break with it.

The decisive text was Andreas Vesalius’s De humani corporis fabrica libri septem (Basel, 1543), a single folio of more than seven hundred pages with a celebrated series of woodcut illustrations attributed to the workshop of Titian and probably drawn by Jan Stephan van Calcar. Vesalius (1514–1564), a Fleming who had studied at Louvain and Paris and who held the chair of surgery at Padua from 1537, based the Fabrica on direct human dissection carried out by himself, on a programme of work in the Paduan anatomical theatre built in 1594 but in a tradition going back to the 1520s. The book corrected, in the most pointed way, more than two hundred errors in the Galenic anatomy of the heart, the blood, the bones, and the nervous system. Vesalius was the pupil of Jacobus Sylvius, the leading Parisian anatomist, and his break with Sylvius was one of the great generational confrontations of the period.

The Fabrica was followed by a generation of anatomical and physiological works: Realdo Colombo’s De re anatomica (Venice, 1559) on the pulmonary circulation; Gabriele Falloppio’s Observationes anatomicae (Venice, 1561) on the human reproductive system; Fabricius ab Aquapendente’s De venarum ostiolis (Padua, 1603) on the venous valves that would be the empirical starting point of William Harvey’s Exercitatio anatomica de motu cordis et sanguinis in animalibus (Frankfurt, 1628). The tradition, often called the Paduan school, was the institutional and intellectual setting in which the new anatomy and physiology was worked out. Andrew Cunningham and Roger French have, in their histories of the Paduan school, set the new anatomy in its long sixteenth-century context.

The new geography and the new world

The third decisive shift was in the geography. The geography of the Latin West in the late Middle Ages was, in the Imago mundi of the Herman of Carinthia (c. 1135) and in the Ptolemy of the Geographia (translated from the Greek into Latin in 1409 by Jacopo d’Angelo da Scarperia), a geography of the three continents of the Old World, of the inhabited world of the oikoumene, and of a generally concentric arrangement of land and sea. The Ptolemy of the Geographia had, in the second century AD, known the world from the Canary Islands to China and from the British Isles to the lands south of the Sahara; the Latin Geographia of the early fifteenth century, as printed in the great Vicenza edition of 1475, gave the humanist reader the same Ptolemaic view. The 1482 Ulm edition added the eleven new maps of the contemporary world that the German humanist Nicolaus Germanus had prepared for the purpose.

The actual geography of the European voyages of the late fifteenth and early sixteenth centuries was, of course, the work of the Portuguese, the Spanish, and the Italian navigators. Bartolomeu Dias rounded the Cape of Good Hope in 1488; Vasco da Gama reached Calicut in 1498; Christopher Columbus made his first landfall in the Bahamas in 1492; John Cabot made his first landfall in Newfoundland in 1497; Pedro Álvares Cabral reached Brazil in 1500; Amerigo Vespucci made his voyages of 1497–1504, the accounts of which were widely distributed in the humanist and vernacular press; Ferdinand Magellan led the expedition that circumnavigated the globe between 1519 and 1522, and Juan Sebastián Elcano brought the Victoria home to Seville. The new world that the Diogo Ribeiro* map of 1529, the Waldseemüller map of 1507, and the Cantino planisphere of 1502 represented was, in cartographic form, a complete rewriting of the Ptolemaic oikoumene. J. H. Parry’s The Age of Reconnaissance (1963) and Felipe Fernández-Armesto’s 1492: The Year the World Began (2009) have set the voyages in the long history of European expansion. The intellectual consequences were worked out in the next two centuries: in Geronimo Mercuriale’s lectures at Padua on the new medicines of the New World, in Jose de Acosta’s Historia natural y moral de las Indias (Seville, 1590), and in the empirical and natural-historical traditions that the Aldrovandi museum at Bologna and the Calceolarius museum at Verona were the first great collections of.

The boundary of knowledge

The science of the long sixteenth century has to be read as a series of long, slow, and incomplete displacements rather than as a “revolution.” The Aristotelian natural philosophy of the universities did not disappear with Galileo; the Ptolemaic astronomy of the Almagest did not disappear with Copernicus; the Galenic medicine of the medical schools did not disappear with Vesalius. What disappeared was the principle that the authorities of the past, however venerable, could be read without observation and without criticism. The Paduan tradition, the Nuremberg tradition, the Bolognese tradition, the Wittenberg tradition, the Parisian tradition, the London tradition, and the Prague tradition were the working communities in which that principle was first put into practice, and from which the science of the seventeenth century — the science of Boyle, Newton, and the Royal Society — was to be developed.