By the late fourteenth century, the Catholic Church had serious problems. The popes had taken up residence at Avignon in 1309, but in 1377 Pope Gregory XI (1330–78) moved back to Rome. The French cardinals were very unhappy about this and elected their own pope as his successor to remain at Avignon. Thus began the schism, when there were two and sometimes even three popes all reigning at the same time. Attempts to reunite the papacy started almost at once and eventually the need for a General Council of the Church was agreed. The first attempt, in 1409, was a failure but in 1417 the Council of Constance appointed a single Pope about whom almost everyone could agree. The dispute now transmuted into a debate about papal power. Above all, no one knew what should happen if the Pope himself was corrupt or a heretic. The argument ran out of steam in the 1430s with the Pope having suffered no diminution of his prerogatives. This was extremely unfortunate, because the next century would see a succession of popes who were obsessed by military power or massive ostentation. This meant they were always in need of money. One of their demands on the pockets of the faithful in Germany would lead to the Protestant Reformation.
Despite the vexations of the Church, the fifteenth century produced several philosophers of note. More significantly, European civilisation recovered its poise after the disaster of the Black Death and enjoyed another spurt of technological progress, the consequences of which would involve the entire globe.
Nicholas of Cusa
The most original thinker of the fifteenth century was Nicholas of Cusa (1400–64) from Germany. His interests included mathematics, philosophy and theology. For his education he travelled to the university of Padua, where he received a doctorate in law, before leading an eventful life mixed up in ecclesiastical politics. In 1448 he was made a cardinal.1 Despite his busy professional career, he still found time to write important books on theology and philosophy.
While returning from Constantinople on church business he conceived On Learned Ignorance, the book that made him famous.2 The title suggests that that book was not meant to be taken seriously, but learned ignorance is actually a method of discovering truths about God based on accepting what we cannot know. Nicholas’s views are not always easy to comprehend but to us, they can seem quite inspired. He argued that in order to reflect God’s majesty, the universe he created would have to be limitless, if not quite infinite. He continues: ‘Therefore, the earth cannot be in the centre … and just as the earth is not at the centre of the universe, so the sphere of the fixed stars is not its outer border.’3 He continues that the earth must also be moving although, and this comes straight from John Buridan, we do not notice because we are riding along with it. Most radically, he reduces the earth to just another star (albeit the most important one) and suggests that alien life forms could exist elsewhere in the universe.4 At the time, no one would have objected to this kind of speculation as long as it stayed hypothetical. As Nicholas could not prove anything, he simply postulated ideas to see what they looked like. He probably never dreamed that within two centuries of his death, his speculations would be found to have been uncannily accurate.
A further short work of his is worth noting. In On Measuring, he set out a method of doing natural philosophy that would soon come to define modern science. We have seen how empirical observation was becoming increasingly popular and how magic encouraged some dabblers to get their hands dirty. But these proto-experiments tended to be observational and qualitative. Nicholas realised that to effectively marry natural philosophy to mathematics required not just careful observation but exacting standards of measurement. Only by carefully weighing, timing or measuring the material from experiments could sufficient data be generated to build a mathematical description of nature. He also appreciated that this sort of painstaking research was both difficult and time-consuming, but urged his contemporaries to apply themselves to the task.5 Sadly, his own official duties left him with no spare time for experiments and no one else took much notice of his proposals. Truly experimental science would have to wait but in this area, like so many others, a medieval thinker had seen the way ahead.
The Crisis of Ancient Geography
Nicholas of Cusa was not the only cardinal with a sideline as a natural philosopher. A central figure at the Council of Constance had been Pierre D’Ailly (1350–1420), a graduate of the university of Paris who was made a cardinal in 1411.6 He was unusual for a senior churchman in that many of his opinions were on the outer rim of orthodoxy. Unlike Nicole Oresme, Pierre was an enthusiast for astrology. Building on the speculations of Roger Bacon, he even managed to predict the French Revolution or, at any rate, a serious upheaval in 1789.7 His other act of prophecy was even more prescient. In a book called Picture of the World, Pierre explained why it would be feasible to sail west in order to reach the East Indies. He made this suggestion based on a very fruitful disagreement between ancient Greek geographers about how large the earth really is.
The best-regarded figure at the time for the circumference of the globe was 252,000 stades, calculated by Eratosthenes (who died around 200BC), a librarian of the famous library in Alexandria. He noted that when the sun was directly overhead in the town of Syrene, it was at 7.2° from the vertical at Alexandria. 7.2° is one fiftieth of the full circle of 360°. Correspondingly, this meant that the distance from Alexandria to Syrene was one fiftieth of the entire circumference of the earth. All he had to do then was measure that distance. He did this by pacing it out, quite a feat for a span of over 500 miles. Alexandria to Syrene turned out to be 5,000 stades, so the earth’s circumference is 250,000 stades.
Unfortunately, no one knows exactly how long Eratosthenes took a stade to be, because the unit comes from the length of a stadium. Its precise length depended on which stadium was being measured. However, we know that the figure only varied between about 170 and 205 yards, which means that his figure for the earth’s circumference was between 24,000 and 30,000 miles. The most likely figure is 202 yards (the length of an Athenian stade) which gives a circumference of 29,000 miles.8 The true figure is 24,900 miles, so Eratosthenes’s calculation gave him a figure that was slightly too large. Nevertheless, the Roman encyclopaedia of Pliny the Elder (AD23–79) used it and thus transmitted it to the Middle Ages. During the thirteenth century, John Sacrobosco reports the same number in his Treatise on the Sphere and it became widely accepted over the next few centuries.9
There the matter rested until the rediscovery and translation of Ptolemy’s Geography, another ancient Greek scientific masterpiece, in 1406.10 Western scholars had long known about Ptolemy’s astronomical compendium, the Almagest, but they previously had had no access to his work on geography.
Like Ptolemy’s other works, the Geography is a technical treatise. It deals with how to make a map of the world using a system of latitude and longitude to plot the locations of cities, islands and other features. The most difficult aspect of the job is how to represent the curved surface of the earth on a flat piece of paper. The bulk of the Geography is taken up by tables of cities and other locations together with their grid references. Taken together, they allow the reader to produce a series of maps, including one of the whole world.
Ptolemy’s map of Europe looks very familiar, except that Scotland’s coast takes a sharp turn eastwards and juts out 300 miles into the North Sea. His map of the world is not entirely alien either, but does have a few features that raise modern eyebrows. India appears to be an island and things get a bit vague around the edges. Naturally, there is no trace of America or Australia. However, the most striking
10. A map of the world according to Ptolemy from an atlas printed in 1482
feature is Ptolemy’s belief that the southern end of Africa loops eastwards and joins on to the far end of Asia. This has the result that land completely encloses the Indian Ocean and means that it would be impossible to sail from Europe to India around the Cape of Good Hope.
The Geography also contained a very significant mistake. Ptolemy estimated that the earth’s circumference was only 180,000 stades, 70,000 stades less than Eratosthenes’s figure.11 This potentially meant that the eastern tip of Asia was not all that far from western Europe. Pierre D’Ailly, taking his inspiration from Ptolemy, suggested that sailing west might be practicable. At about the same time, a popular book of travellers’ tales under the name of Sir John Mandeville included a story about a Danish sailor who had circumnavigated the earth.12 Whoever wrote Mandeville’s book had probably never travelled further than his local library, but the book was fantastically popular and much more influential than Marco Polo’s more truthful account.
Ptolemy’s work on geography decisively demonstrated that the ancient authors completely disagreed on basic questions. There was just no way to reconcile the various opinions that they expressed. For instance, Aristotle divided the earth into five different climatic zones. The northern and southern polar regions are too cold and icy for anyone to live there. The tropics are also uninhabitable because they are too hot.13 Pliny described the equator itself as a ring of fire that completely cut off the northern hemisphere from the southern. Between the poles and the tropics were two temperate regions. According to him we lived in the northern temperate region and there was another in the south, although the ring of fire meant that we could never travel there.14
This raised some tricky theological problems, and we saw in chapter 2 how Virgil of Salzburg may have encountered trouble over the issue in the ninth century. Christians wanted to know if anyone lived in the southern temperate region and if so, how they had got there. After all, every animal on the planet should be a descendant of one of the breeding pairs which Noah loaded onto his Ark during the Great Flood described in the book of Genesis. When the flood waters receded, the Ark came to rest on Mount Ararat in Turkey from where all the animals went their way. However, if there really was a ring of fire at the equator, then there was no way for the animals from the Ark to reach the southern hemisphere. Worse still, if humans were living there, how were Christians supposed to go and save their souls if the equator formed an impenetrable barrier?
Ptolemy presented a different view. He made no mention of the tropics being uninhabitable and clearly believed that reaching the southern hemisphere was simply a matter of sailing far enough south. Then, in 1473, the argument was settled decisively in Ptolemy’s favour when a Portuguese ship, exploring the western coast of Africa, crossed the equator. It was a point against Aristotle and raised the question of where else he might be mistaken. The Portuguese soon proved that Ptolemy was fallible too. Bartolomeu Dias (d. 1500) rounded the Cape of Good Hope in 1488 and showed that it was possible to reach the Indian Ocean by sea. A route to the Spice Islands of the East Indies lay open.15
The spice trade was a great deal more diverse than we might imagine today. Although the export of nutmeg, cloves and pepper was an extremely lucrative venture, the word ‘spice’ included any imperishable high value, low volume cargo. Ivory, resin, amber, glue, perfume, wax, dye and sugar all came under the category of spices.16 Along the old Silk Road, threading its way across central Asia, tollbooths took a cut at each national border. That is, if the route was open at all. Alternatively, Arab traders could ship the spices to the Red Sea and carry them by camel train the short distance to the Mediterranean. Once the goods had reached the east coast of the Mediterranean Sea, Venetian ships transported them to western Europe. For Portugal and Spain, the only way to get a share of the trade was to find another route to the Far East. The Portuguese controlled the route around Africa and so the Spanish would have to consider another direction.
The Discovery of the New World
Christopher Columbus (1451–1506) was born in the mercantile republic of Genoa and decided to seek his fortune on the sea rather than enter the family wool business. He was self-taught and must have been a man of exceptional talent to persuade monarchs to let him sail off into the unknown at their expense. Columbus had a different idea about the best sea route to the Spice Islands of the East Indies. He decided that the quickest and safest direction would be to sail west.
Columbus’s conjectures received support from Pierre D’Ailly’s Picture of the World. His own copy still survives and contains many marginal notes in the navigator’s handwriting. D’Ailly, writing in 1410, still believed that the tropics were too hot to live in, but Columbus noted in the margin: ‘The torrid zone is not uninhabitable because today the Portuguese navigate through it. Indeed, it is very populated.’17 D’Ailly also gathers some evidence from various ancient authors, emphasised by Columbus in his annotations, that only ‘a small sea’ lies between Spain and the Far East which should be ‘navigable in a few days.’18 Finally, D’Ailly uses Ptolemy’s figure for the circumference of the earth – which is only about 21,000 miles.19
Based on his research, Columbus was completely convinced that the far east of Asia was only 2,500 miles from the west coast of Spain. He must have reached this figure by taking the largest possible figure for the length of Asia and combining it with the smallest for the earth’s circumference. The true distance between Europe and Japan is closer to 12,500 miles and so Columbus was very, very wrong.20 He was also very lucky. Imagine his fate if the Americas had not existed. Columbus and his little fleet would have sailed on in the endless expanse of ocean with no chance of ever being able to reach the East Indies before succumbing to thirst, starvation or disease. His sailors were well aware of this and it was for this reason, rather than any concerns about the edge of the world, that they were unwilling to sail west. In Columbus’s defence, he may have been aware of travellers’ tales from northern Europe about Viking discoveries to the west of Greenland. He claimed to have visited Iceland, or Thule as it was then known, in 1477 and to have sailed 100 leagues beyond it.21 As it was, Columbus made landfall in the Caribbean exactly where he expected to find the East Indies. It is hardly surprising that he went to his grave convinced that his mission had been a success.
By 1550, the new geography was settled and the map of the earth no longer looked anything like the ancient Greeks said it should. The cornerstones of ancient geography had been the division of the earth into five climatic zones and the existence of only one great land mass. Both were wrong. Theological arguments about the inhabitants of the antipodes were also rendered moot. As a contemporary writer noted, ‘not only has this navigation confounded many ancient writers about earthly things, but it has also given some anxiety to the interpreters of the Holy Scriptures.’22 The continent of America threw up exactly the same theological problems that had previously been raised by the antipodes. People realised this but could hardly argue with the brute facts. As Robert Record put it in his book Castle of Knowledge (1556), the existence of new lands was as obvious as the existence of those testified by the Bible and, whatever the theological concerns might be, there was no getting away from it.23 The remarkable thing is how easily the new geography was accepted and how little effect it had on natural philosophy. Initial hopes that the Americas might be small islands or contain sea channels through to the Pacific Ocean quickly evaporated.
The great navigations of the fifteenth century represent Europe expanding its boundaries well beyond those it had inherited from the ancient world. At the same time, the last vestige of the Roman Empire itself was finally conquered in an event that seemed to be nothing less than a cataclysm: the extinction of Byzantium.
The Fall of Constantinople
By 1453, the territory of the Byzantine Empire had been reduced to the area enclosed by the walls of the city of Constantinople, and now the new Ottoman Sultan Mehmet II (1432–81) was determined to snuff it out. His army numbered 100,00024 and his fleet controlled the harbour of the Golden Horn. The only thing standing between Mehmet and the city’s motley group of a few thousand defenders under the leadership of Emperor Constantine XI Paleologus (1404– 53) were the mighty land walls. These walls had been built in the fifth century and had never been breached.
The land walls still stand today. To reach the centre of Istanbul from the airport, you have to drive through them. The ruined sections are imposing enough, but in the sectors where they have been restored they present a formidable obstacle, far higher and broader than any other castle or city walls from the Middle Ages.
To penetrate this barrier, Mehmet needed the latest technology from western Europe. It arrived in the guise of a Hungarian engineer called Urban who promised Mehmet that he could build a cannon large enough to blow down the walls. To be fair, he had already offered his services to the Byzantines but had been rebuffed over his fee. The bombard he constructed for the Turks was said to be 27 feet long and able to fire a 1,340lb ball a mile.25
These figures are doubtless exaggerations, but the weaponry available to the Sultan was surely formidable.26 A siege gun from precisely this era survives in Edinburgh Castle and allows us to deduce some rather more sensible figures for the size and performance of Mehmet’s weapon. The Edinburgh gun, known as Mons Meg after the Belgian city of Mons where it was first tested, was made in about 1449 and given to the king of Scotland by the Duke of Burgundy to stir up trouble with the English. It weighs over six and a half tons and takes a 400-pound ball. Its range from the top of Castle Mount was about two miles.
In 1680, Mons Meg’s barrel exploded and it was never fired again. The burst gun allows us to clearly see how it was constructed. Thirty-seven iron hoops were heated and slotted onto a thin-walled inner tube made of 25 iron staves. The tube formed the inside of the barrel while the thick iron rings provided a reinforced exterior. As the iron cooled, it shrank and formed a tight fit around the inner tube.27
By the day of the final assault, the siege of Constantinople had lasted two months but in the end, the Sultan’s cannons did the job. The vast volume of stone that made up the land walls had been slowly chipped away. During the small hours of the morning of Tuesday, 29 May 1453, with the walls breached, the final assault began. The defenders manned the ramparts and resisted long after the cause had become hopeless. The first two waves of attackers were beaten back, but as a last resort Mehmet sent in his elite forces, the Janissaries. Finally, they managed to scale the wall. The Emperor himself was seen where the fighting was thickest. When the battle was over, Mehmet ordered that his body be recovered for an honourable burial, but it was so mutilated that it could not be recognised. A decapitated corpse was eventually identified on the basis of the imperial regalia on its socks.28
As was the custom in war, when the city fell, the Turks fell on it in an orgy of pillage and destruction. The exquisite sixth-century cathedral of Hagia Sophia was saved by its immediate rededication as a mosque, but little else has survived of Christian Constantinople. Ironically, the finest remaining collection of Byzantine art is that looted by the fourth crusade in 1204 and still on display at the Cathedral of San Marco in Venice. The Venetians had led the crusaders who sacked Constantinople during an abortive attempt to retake the Holy Land. Even though the Byzantines had managed to retake their capital a few decades later, the crusaders had fatally weakened them and made their eventual conquest by the Turks inevitable. The fall of Constantinople in 1453 to an Islamic army caused consternation in western Europe. But as Catholics bewailed the loss of eastern Christendom, they only had their own crusaders to blame.
By supplying Mehmet with the weaponry and expertise he needed to breach the mighty land walls, the West had also contributed more directly to his victory. Without the cannons of Urban, taking Constantinople would have been much harder, if not impossible. Although the knowledge of gunpowder had been around for centuries, it took a long time to produce reliable weapons that used it. In the 1420s, the technique of granulation was developed to make gunpowder safer and more reliable. Mixing it with brandy or another alcoholic liquid caused the powder to coagulate into course lumps. This made for easier handling and a more even combustion.29 Advances in metallurgy, principally the development of the blast furnace, meant that iron became a strong enough material for cannon barrels and provided an alternative to bronze. Blast furnaces also turned out metal with a lower melting point than traditional means of forging iron so it could be cast into cannon balls or other shapes using clay moulds. The Turks had used a huge bombard during the siege of Constantinople, but smaller-calibre cannon turned out to be a more effective battlefield weapon.
At the smaller end of the scale, handguns required a failsafe firing mechanism before they could displace the crossbow. Such a weapon appeared shortly before 1500 in the form of the matchlock musket, which had an enclosed mechanism and a spring-loaded trigger.30 Guns meant that Europeans could dominate almost every other people that they came up against. The English longbow, so instrumental during the Hundred Years War against France, was probably a superior weapon to the musket. The problem was that a bowman needed exceptional strength in his right arm to pull back the drawstring. Training began at an early age and maintaining a company of archers was expensive. The early gunpowder weapons may have been less effective in combat, but any fool can fire a gun. This made musketeers cheaper and consigned the longbow to obsolescence.
The Invention of the Printed Book
The development of guns made men better at killing other men. Printing is a pacific invention, but probably changed the world even more than the black powder. Like gunpowder, print originated in the Far East where people had used carved woodblocks and metal type for centuries. In Europe, short religious pamphlets, consisting of little more than a devotional picture and a short explanatory text, appeared in the late fourteenth century. These too used woodblocks. Stationers found that they were only economical for large print runs of standard documents, because they had to cut an entire block that they could not reuse for a different job.
The secret of paper had also travelled from China to Europe during the Middle Ages. Europeans had had to use parchment or vellum as their main writing medium since late antiquity. This is made from animal skins and was ruinously expensive. A paper mill is recorded in central Italy by 1276 and in France by 1348.31 Although it was hardly cheap, paper was already well on the way to replacing parchment by the fifteenth century.
The father of printing was Johann Gutenberg (c.1398–1468), a metallurgist from Mainz in Germany. While the idea of printing was not new and paper already existed as a suitable material, Gutenberg had to make several intuitive leaps that mean we really can celebrate him as the inventor of the modern printed book. His greatest advance was moveable metal type. He cast the type for every letter separately so that the typesetter could rearrange them for each new page. Next, Gutenberg needed an ink that adhered to paper and did not smudge. He experimented with various oil-based inks, before settling on a mixture of soot and turpentine suspended in walnut oil. Finally, he adapted the old-fashioned wine or olive oil press into a device for bringing type and paper together under pressure.32
Gutenberg’s first printed book was a short Latin grammar, but his great Bible of 1455 irrefutably demonstrated the potential of the new technology.33 The Latin alphabet gave European printers a significant advantage over many Asian countries. Because European languages employ only about 25 letters each, a printer needs only a small assortment of type to be able to print absolutely anything. Chinese and other oriental languages have a different symbol for each word, necessitating a vast collection of different type. This rendered the capital cost of setting up a printing operation prohibitive and increased the time required to typeset a page.
The advantages of the printed book went well beyond cost. Of course, they were cheaper than manuscripts, but they were also much more legible. Better still, they had the potential to be more accurate. Unfortunately, poor editing blighted many early printed books. ‘There is always the carelessness of printers to contend with’, one noted writer moaned in his introduction to the Natural History of Pliny the Elder in 1525.34 This meant that errors tended to proliferate through many copies rather than staying confined to a single manuscript. At least this gave publishers a useful marketing tool when no copyright existed. They could always insist that their version of a book was free of the gratuitous errors that allegedly plagued rival editions. ‘Newly corrected and amended’ was among the most common blurbs on the covers of early printed books.
The earliest of books printed included the works of the scholastic natural philosophers whom we met in the last chapter. Several of the most important books by John Buridan and Nicole Oresme were printed in Paris. Richard Swineshead was published in Venice, the city that dominated the early market in scientific texts. The 1494 Venetian edition of William Heytesbury’s Rules for Solving Logical Puzzles included not just the mean speed theorem but also Nicole Oresme’s diagrammatic proof. Most popular of all was Albert of Saxony’s Book on Proportion, which went through no fewer than nine editions and included plenty of references to the work of his masters Buridan and Oresme. All this activity means that it would be quite wrong to think that the discoveries of medieval thinkers were ‘lost’, hidden in impenetrable manuscripts and gathering dust in monastic libraries. The fact that printers were willing to invest the capital outlay on many editions of these works shows that there was demand for them. It is true that some of these early books are a struggle to read, making use of arcane abbreviations and an ugly gothic typeface. But at the time they were a joy compared to the effort of deciphering a manuscript.
The invention of printing meant that the scientific advances of the Middle Ages were preserved even when the intellectual tide turned against them. The books of Albert of Saxony and William Heytesbury were about to become deeply unfashionable, but because they were already in print they remained available to people who knew where to look. In the remainder of this book, we will hear the story of the men who built on this vital but unloved legacy to bring modern science into being. First, though, we must meet a group of scholars and gentlemen who turned the word ‘medieval’ into an insult and sought to forget everything they owed to their immediate past in favour of glorifying the residues of the ancient world. These men have become known as the humanists.