One of those historical myths that enjoy popular currency, even though they cannot survive the scrutiny of serious historical study, is that, at the dawn of the Christian era, there was a thriving Hellenistic scientific culture that Christianity — through some supposed hostility to learning and reason — methodically destroyed; and that this Christian antagonism to science persisted into the early modern period - as is evident from Galileo's trial in Rome - until the power of the Church was at last broken, and secular faculties of science began to appear.

[The geocentric view of the universe postulated by the brilliant mathematician and astronomer Ptolemy, as portrayed by the German mapmaker Andreas Cellarius in his celestial atlas of 1660, Harmonia Macrocosmica. Ptolemy's system held sway until the modern development of new theories of motion]

This story is impossible to reconcile with the historical evidence, ancient, Medieval, or modern. It misrepresents the characters both of Hellenistic science and of early Christianity, as well as that of Medieval intellectual culture; and it entirely belies the fascinating reality that, in the 16th and 17th centuries, Christian scientists educated in Christian universities and following a Christian tradition of scientific and mathematical speculation overturned a pagan cosmology and physics unchallenged since the days of Aristotle.

Ancient and Medieval Science

There never was a particularly advanced culture of Hellenistic 'science' — at least, not in the sense the word has now: a systematic and analytic use of experiment and observation to correct and refine hypotheses. Careful astronomical observation had led to the invention of the astrolabe, some of the remedies prescribed by medical 'science' were effective (or, at least, not harmful), some fine work in the geometry of optics was achieved by Ptolemy (c. 100—c. 170), and a few clever mechanical inventions had appeared by the end of the first century ad; but Greek science had never been much interested in concrete experiment, and as a whole had declined towards encyclopaedism and commentary before the Christian age. But research of a sort did persist in Alexandria, and was pursued during the Christian period as avidly by Christian scholars as by pagan.

Cosmology was at once the most elaborately developed and the most static area of scientific erudition. From antiquity through the late Middle Ages, almost all scientists - pagan, Christian or Muslim - accepted some version of the Aristotelian model of the universe, and some version of Ptolemy's attempt to describe a geocentric universe mathematically. According to the former, the stationary earth is surrounded by a series of revolving concentric crystalline planetary spheres, the lowest of which contains the moon; the 'sublunar' realm is the region of change and decay, of the elements of air and fire, earth and water; the 'superlunar' realm, however, is composed of the 'quintessence' or 'aether', and there all is changeless.

Beyond the farthest planetary sphere lies the sphere of the fixed stars. And the whole machinery of the cosmos is driven by its outermost sphere, the 'first moved'.

[A statue of Nicolaus Copernicus is his home town of Torun, Poland]

Ptolemy's exquisitely complex model of the heavens was an attempt to make this model of reality somehow consonant with the observable movements of heavenly objects - including the apparent 'retrograde' movement of certain planets — but this, in the end, was impossible. Ptolemy was forced to introduce such bizarre devices as 'eccentrics' (extraterrestrial axes for certain planetary orbits), 'equants' (imaginary secondary axes that allowed orbits to be measured as mathematically uniform) and 'epicycles' (small local orbital axes located within the planetary spheres) into his calculations. Nor did Ptolemy trouble overly much about empirical observation (one could disprove his description of the lunar cycle, for instance, simply by looking at the moon several nights in succession). None of his mathematical devices, moreover, was compatible with Aristotelian physics, but — while scientists occasionally attempted to improve upon the model thus produced - few ever thought to reject it outright.

One exception to this rule was the sixth-century Christian scientist John Philoponus, who speculated that heavenly bodies are in fact mutable, that above the atmosphere there was perhaps a vacuum, that the stars were not (as pagan scientists believed) spiritual intelligences, but merely masses of fire, and that the planets might move by an 'impressed' impetus. A few later Muslim astronomers addressed Philoponus' ideas, without adopting them, and by that route they entered into Western Christian scholastic science, where they were taken up and explored by men like Thomas Bradwardine (c.1290-1349), Richard Swineshead (ft. 1348), Jean Buridan (1300-58) and Nicholas Oresme (c. 1320-82).

The Heliocentric Revolution

Nicolaus Copernicus (1473-1543) was a beneficiary of this tradition; but he was the first Christian theorist explicitly to argue for a heliocentric cosmos, in his treatise De revolutionibus orbiutn coelestium (published 1543). His argument was not particularly compelling, as it happens; his mathematical models were defective and almost as complicated as Ptolemy's (and as fraught with 'epicycles'). His basic model did seem to explain why Mercury andVenus remain always near the sun, but so did the later system of Tycho Brahe (1546-1601) according to which all the planets above revolve around the sun, while only the sun revolves directly around the earth. By the time of the trial of the most famous defender of the Copernican theory, Galileo Galilei (1564-1642), many of the best astronomers (a great many of whom were Jesuits) had adopted the 'Tychonic' model.

When challenged by theologians, Galileo quite correctly appealed to the Church Fathers to defend the claim that the scriptures ought not to be mistaken for cosmological treatises. In the 17th century, though, under the pressure of Protestant criticism, the Catholic Church had become much more diffident in the latitude with which it read scripture, and had begun to incline towards greater literalism. That said, in the years leading up to his trial, Galileo had enjoyed the esteem of many prominent churchmen; several Jesuit astronomers helped to confirm many of his telescopic observations; and even when his Copernican sympathies became clear in 1613 he was not censured by ecclesial authority. Galileo's most important admirer and ally in the Church, in fact, was Cardinal Maffeo Barberini (1568-1644), who in 1623 became Pope Urban VIII - the very man who would ultimately command Galileo to recant.

Galileo, however, was a frequently unpleasant man, who often refused to give other scientists credit for their own discoveries, belittled those he saw as rivals (such as Johannes Kepler), and insisted on provoking disputes. His demands for unconditional acceptance of his theories led to an ecclesial consultation in 1616. When he failed to produce a single convincing proof for his position, the consultation admonished him against teaching Copernican theory as a fact. Even so, Urban himself encouraged Galileo to write the book that became the Dialogue concerning the Two Chief World Systems, the Ptolemaic and Copernican (1632), enjoining only that it include a statement to the effect that Copernican theory was only an unproven hypothesis. Galileo did include such a statement in his dialogue, but placed it on the lips of a clownishly obtuse character named Simplicio.

Galileo on trial in Rome. It is a myth that Galileo was tortured by the Roman Inquisition (though, in keeping with the unsavoury forensic procedures of the time, he was reminded that torture could be applied as a penalty for perjury). But he definitely was ordered to recant his Copernicanism, an instruction with which he complied.

This seemed an unwarranted insult of a generous friend; Urban took offence and resolved upon a trial. Moreover, as it turned out, Urban was quite right about the unproven nature of the Copernican theory. For all his brilliance as a physicist, Galileo was an amateur astronomer at best, and seemed unaware how mathematically and empirically incoherent Copernicus' book was. The only evidence he provided for the Earth's movement was a theory about the tides that was completely irreconcilable with observable tidal sequences. He could have defended heliocentrism better if he had been willing to adopt Kepler's theory of elliptical planetary orbits — of which he was aware — but he was loath to do so.

The ultimate effect of Rome's authoritarian meddling was to make the Church hierarchy appear ridiculous. The case was, though, an aberration, and not a true indicator of the relation between the Catholic Church and the sciences. In fact, the Church was a generous patron of the sciences, while the Jesuits fostered many of the most original scientific minds of the age. But the embarrassment created for the Catholic Church by Urban's outraged pride has never entirely faded.


Johannes Kepler (1571-1630) was a brilliant astronomer, natural scientist, theorist of optics and mathematician, but was also a metaphysician, an astrologer and something of a mystic; in his youth, he had intended to become a theologian, and to the end of his life he regarded his scientific endeavour as a sacred vocation, which allowed him to discover the sublime harmonies informing creation, and the ways in which the Trinity is reflected in them. In Copernicus' heliocentrism - which he encountered in the early 1590s - Kepler believed he had found (if only in intuitive form) a model of the cosmic order that adequately mirrored the divine governance of the universe: the sun's centrality being, as it were, a physical symbol of the Father, Son and Holy Spirit ruling over and guiding all things. And even in his discovery of the elliptical shape of planetary orbits (in which he was aided by Tycho Brahe's meticulously precise astronomical observations) he believed he could discern depths of geometric perfection in which the divine archetypes of all things shone forth.

Though a devout Lutheran, Kepler had no interest in sectarian disputes; he was on good terms with many Calvinists and Catholics (with many friends and protectors among the Jesuits). He was content to labour under Catholic or Lutheran princes; he was not, however, shown comparable tolerance. At one point, he was expelled from the Lutheran communion; at another, Catholic authorities confiscated his books and told him to send his children to mass.

Kepler, though, laboured on, inspired to the end by his vision of a cosmic order of intricate beauties and delicate concords. The work that probably best expresses his vision of reality is his Harmonices Mundi of 1619, in which he gave free rein to his Christian Platonist and semi- Pythagorean tendencies. He described there the structure of the cosmos in terms of a 'universal music', found in all the geometric ratios of the natural order, and especially in the subtle consonances - and spiritual influences -between heavenly bodies and the human soul.