What Copernicus and Darwin Did

Most histories of science take the year 1543 as the starting date for what is known as ‘the scientific revolution’. In that year appeared two significant treatises: Nicolaus Copernicus’ On the Revolutions of the Heavenly Spheres and Andreas Vesalius’ On the Structure of the Human Body. The first revived a heliocentric theory of the universe, but with better mathematics to support it than was available to its first proponents among the philosophers of classical antiquity. Because it was associated by Renaissance humanist scholars with Pythagoras the heliocentric theory was known as the ‘Pythagorean Theory’.

The second revolutionary treatise, Vesalius’s Structure, put the study of human anatomy on a firm observational basis for the first time. Prior to these two works, theorising about the natural world was derived from the frequently misleading authority of the ancients, found principally in Aristotle, Galen, and Pliny the Elder’s Natural History.

But Copernicus and Vesalius were not the first to challenge the ancients. The initial crack in their edifice authority was a short book, published fifty years before Copernicus’s Revolutions, by Nicolai Leonicini of Ferrara. His little volume was called On the Errors of Pliny and Other Medical Writers. It details the mistakes in Pliny’s Natural History, which had hitherto been regarded not just as authoritative but encyclopaedic. Leonicini’s original aim had been to establish a correct text of Pliny’s book, into which many textual errors had crept over the centuries as a result of the weariness, inattention or other lapses of successive generations of manuscript copyists. The advent of printing in the second half of the fifteenth century had generated an enormous demand for the writings of the ancients, and Leonicini had been commissioned to produce a correct copy of the text for the printers. While collating the various versions he engaged in correspondence with Angelo Poliziano to discuss puzzles thrown up by the endeavour, and this correspondence served as the basis of his book. For in the process of examining the different texts Leonicini had to deal with the question whether the errors were scribal or the fault of Pliny himself. He concluded that what Pliny wrote ‘was insufficiently researched and confirmed by him’. That was both a comment on the fallibility of the ancient authorities and a statement of scientific principle, and together they constituted a major first step towards modern science.

Copernicus’s contribution was far more consequential. While studying at Krakow University he became intrigued by the contradictions between the astronomical systems of Aristotle and Ptolemy, the two chief but competing ancient authorities on the nature of the heavens. Pursuing the ideas thus sparked, he wrote an early version of his heliocentric model in 1614 for private distribution; in the following decades he worked out the thesis more fully, but did not publish it, fearing what its reception might be. In 1533 his ideas were explained to Pope Clement VII and two cardinals, who – persuaded by the disclaimer that it was ‘only’ a heuristic model and not intended as a true representation of the heavens – were entertained by its ingenuity, and left it at that. It was not until full publication in 1543, the year Copernicus died – legend says that he was brought a printed version of the book on his deathbed – that controversy broke out, and even then in a minor way. Indeed it was scoffed at – for if the earth were rushing through space one would feel the wind in one’s hair; if it were revolving, one would be hurled off its surface; it all seemed too absurd.

It was not until the end of the century that serious efforts were made to suppress the theory. Between publication of the Revolutions and the century’s end the Jesuit Order had come into existence explicitly to combat Protestantism and the Reformation triggered by Martin Luther. The Jesuit’s educational curriculum – the Ratio Studiorum (schedule of study) – prescribed that ‘In logic, natural philosophy, ethics and metaphysics, Aristotle’s doctrine is to be followed.’ This instruction was issued by Francis Borgia – now known as St Francis Borgia, who was then General of the Jesuit order – in a memorandum specifying that no one is allowed to ‘defend or teach anything opposed, detracting, or unfavourable to the faith, either in philosophy or theology. Let no one defend anything against the axioms received by the philosophers, such as: there are only four causes, there are only four elements, there are only three principles of natural things, fire is hot and dry, air is humid and hot. Let no one defend such propositions as that natural agents act at a distance without a medium, contrary to the most common opinion of the philosophers and theologians . . . This is not just an admonition, but a teaching that we impose.’

‘This is a teaching that we impose.’ It is not surprising therefore that the new ideas advanced by science were now greeted with vigorous opposition and sometimes persecution. Salient victims were Giordano Bruno, Giulio Cesare Vanini and Galileo. Bruno was charged with many heretical views, but chief among them espousal of the Copernican astronomy, and was burned at the stake in Rome’s Campo dei Fiori in 1599. Vanini met the same fate in the Place du Salin in Toulouse in February 1619, though his execution was even more horrible; charged with being an ‘atheist and blasphemer’ his tongue was cut out before he was strangled and burned. He became an object of hatred for opponents of the new science, who took its naturalistic approach to entail a wholesale rejection of religion. Accordingly he was subjected to a vitriolic denunciation by a Jesuit named François Garasse, who described him as the very paradigm of a threat to religion and society. A hundred years later Pierre Bayle defended Vanini as a martyr for the cause of science, but in his own day the threat posed by his views was more than enough to demonise him. He was denounced to the authorities by one of his pupils, who reported that he ‘mocked at sacred things, vilified the Incarnation, refused God, attributed everything to fate, adored nature as the bounteous mother and source of all being’, and the charges against him said that he had fallen into impiety and sacrilege and disgraced his priest’s habit. The evidence against him was all too clear; it was there to see, explicitly, in his book The Secrets of Nature. Toulouse’s authorities acted against him because ‘the unfailing attraction of novelty for the young brought him many disciples, especially from amongst the young men fresh from school’. Among the views Vanini expressed were that men do not have souls but die as other animals do, and that because the Virgin Mary was a woman like any other she needed to have sexual relations to get pregnant. Such outrageous remarks were taken to be licensed by the scripture-controverting new theories of the heavens in Copernicus’s treatise.

It is interesting to note, by way of aside, that the curriculum of the Jesuits was more behind the times even than it appears. Paracelsus and the alchemists had already rejected the ancients’ ‘four elements’ and substituted the tria prima doctrine, nominating mercury, salt and sulphur as the basic constituents of all things.

In 1615 a Carmelite friar called Paolo Antonio Foscarini sent the Vatican’s Cardinal Bellarmino a booklet arguing that Copernicus’s model is consistent with scripture. Bellarmino replied that ‘If there were a real proof that the Sun is in the centre of the universe, that the Earth is in the third heaven, and that the Sun does not go round the Earth but the Earth round the Sun, then we should have to proceed with great circumspection in explaining passages of Scripture which appear to teach the contrary.’ And he reminded Foscarini that ‘As you are aware, the Council of Trent forbids the interpretation of the Scriptures in a way contrary to the common opinion of the holy Fathers. Now if your Reverence will read, not merely the Fathers, but modern commentators on Genesis, the Psalms, Ecclesiastes, and Joshua, you will discover that all agree in interpreting them literally as teaching that the Sun is in the heavens and revolves round the Earth with immense speed, and that the Earth is very distant from the heavens, at the centre of the universe, and motionless. Consider, then in your prudence, whether the Church can tolerate that the Scriptures should be interpreted in a manner contrary to that of the holy Fathers and of all modern commentators, both Latin and Greek.’

Bellarmino’s chilling warning – ‘in your prudence’ – could not have been more explicit. The fates of Bruno and Vanini demonstrated how mortally dangerous espousing such views could be. If at his trial Galileo had not agreed to renounce his adherence to the Copernican view, he would have met the same fate.

Galileo’s arrest and trial was triggered by the publication in 1632 of his Dialogue Concerning the Two World Systems. [Here a full account of the trial and what was at issue in it, and of Galileo’s recantation.] The trial was the last great push by the Church to stem the advance of science in its confutation of the literal interpretation of scripture. The book was placed on the Index of Forbidden Books, and the Church did not revoke its condemnation of Galileo until 1992, though it did not condemn the judges who had condemned him, saying that they had ‘acted in good faith’ in the circumstances of the time.

Now consider the fact that a mere half century after Galileo’s trial, in 1686, it was possible for the Cartesian philosopher Bernard de Fontenelle to publish his Conversations on the Plurality of Worlds. In it Fontenelle introduces and explains the nature of the universe as conceived by the seventeenth century’s ‘new (Copernican) philosophy’, contrasting it to the geocentric view it displaced and drawing out the implications for humankind’s self-understanding. The account he gives of the Copernican view is intended as a preface to his argument that because all stars are suns, it is likely that there are many planets revolving about them, bearing life. ‘The universe’, Fontenelle wrote, ‘is but a watch on a larger scale; all its motions depend on determined laws and the mutual relations of its parts . . . It is now known with certainty . . . that Venus and Mercury turn round the sun, and not round the earth; on this subject the ancient system is absolutely exploded . . . At the appearance of a certain German named Copernicus, astronomy became simplified; he destroyed all the unnecessary circles [of Ptolemey], and crushed to pieces the crystalline firmaments [of Aristotle]. Animated with philosophic enthusiasm, he dislodged the earth from the central situation which had been assigned it and in its room placed the sun…The planets were no longer supposed to perform their revolutions round the earth, and enclose it in the centre of their orbits . . . They all turn around the sun; the earth itself not excepted.’

Had Fontenelle lived seventy years earlier, at the date of Bellarmino’s letter to Foscarini, or fifty years earlier at the time of Galileo’s arrest, he could not have published these views freely, without fear of punishment or proscription.

Consider even more pertintently the excitement of Jeremiah Horrocks and William Crabtree when, on 24 November 1639, they made a spectacular scientific observation: a transit of Venus – the visible passage of the planet Venus across the face of the sun. Horrocks had calculated the date of the transit from Kepler’s Rudolphine Tables of planetary motion, based on the Copernican model and published twelve years earlier. It was a classic case of testing a theory by observation; the two amateurs saw what they expected to see, namely, the black dot of Venus inching its way across the brilliant image of the sun projected onto a card in Crabtree’s attic. Horrocks described his friend as standing ‘rapt in contemplation’ for a long time, unable to move, ‘scarcely trusting his senses, through excess of joy’. They knew of course that they were not making a discovery. Copernicus’ work and Galileo’s telescopes had between them already refuted the claim in Psalm 104 verse 5, cited by Bellarmino in his reply to Foscarini, that the earth had been ‘set on its foundations, so that it should never be moved’. What was new was that they were interpreting what they witnessed – a planet travelling on an inner orbit between the earth and the sun – according to an account of the universe’s structure radically different from predecessor accounts; and with it a completely different set of implications for almost everything else humanity foundationally thought, hoped and wished to believe.

What a momentous change, therefore, took place in the period between Copernicus and Darwin. Their enquiries moved humankind both from the centre of the universe and from the summit of creation, to a small rock in the outer margins of an ordinary galaxy among billions of galaxies, and to a place near the back of the queue in the biological crowd on that rock. It is a stupendous reorientation. It is true that even today, in the age of science and technology, some billions of people have not yet grasped this shift of view, still less its implications; but what is now the belief only of religious literalists or those who know little or no science was once not only official orthodoxy but unquestioningly believed by almost everyone. The large and powerful grip of pre-scientific outlooks remain.