Generation 458, 1140-1160. Measuring the world

This generation saw the appearance of a new style of church architecture in northern France.  Nothing like it had been seen before. As with all innovations, it was able to appear because of a combination of circumstances: the opportunity, the motivation, and the people to put it into effect.

First, the opportunity. The latin world in the previous generation had seen a publishing sensation. Adelard of Bath had travelled to the moslem world in search of learning, as had so many others. He was away for seven years, spending most of them in Antioch in present-day Turkey. There he translated books from arabic into latin. His translation of Euclid’s Elements of Geometry was world changing. If you studied geometry at school, a lot of it can be directly traced back to this book, originally written as a textbook by Euclid of Alexandria in the third century BC. A triangle has 180 degrees? Euclid. If you draw a diameter of a circle, then draw a line from each end of the diameter to any point on the circumference, they will meet at right angles. Ditto, Euclid. Pythagoras’ theorem (3 squared plus 4 squared equals 5 squared is the best known example) can be traced to Euclid’s Elements.

As well as the content of the book (which meant that buildings could be designed more effectively than before) Euclid’s method of reasoning was simple, irrefutable and new to the latin world. He set up a series of five axioms, which now seem self-evident. The first axiom, for example, is that a straight line is the shortest distance between two points. He went on to introduce problems, and solved them with logical proofs.

islamic arch

Euclid’s work was well known in the islamic world. This arch from Madrid in al-Andalus, from the previous century, would have been impossible to build without an understanding of the principles of geometry. The pointed arch was a regular feature of islamic architecture.


This prayer niche from the Ibn Tulun mosque in Cairo clearly shows the pointed arch. It was built three hundred years previously, in the ninth century. 

But it was new to the latin north. Adelard’s translation went to the cathedral schools, where it encountered a different culture. It was not by accident that the church was called the Roman Catholic church. It continued the Roman Empire’s love of large structures. Large churches were not new, therefore, but what this technology allowed was a new departure in their construction. Now they could let the light in, applying the same skills in a very different expression.

Saint-Denis in Paris, Sens in Burgundy, Laon in Picardy – all were rebuilt in the new style in this generation. The builders treated the stone as a framework for the windows, using rib-vaulting and pointed arches, and filled the windows with coloured glass (another technique learned from the moslem world).

Sens cathedral

Here is the interior of Sens cathedral, with the soaring columns and huge windows of the new Frankish style, now known as Gothic.

Five centuries later the architect of St Paul’s Cathedral in London, Sir Christopher Wren, came to the same conclusion. In his ‘Parentalia’ or Memoirs, he writes, ” … what we now vulgarly call the Gothic, ought properly and truly to be named the Saracenic architecture refined by the Christians…”

In 1145 Chartres Cathedral burned down, and the opportunity was taken to rebuild it in the new style. The project was not completed until the following century, but this is where it started. There is a statue of Euclid at Chartres, as one of the representatives of the liberal arts. Luckily for us, Chartres became a backwater over the subsequent centuries, overshadowed by Paris. This meant that nobody could afford to modernise the cathedral, and so it can still be seen largely as it was eight centuries ago.

The word ‘geometry’ literally means ‘earth measuring’. The same rigorous enquiry found different expression in the south of Europe during this generation, but applied to geography (‘earth drawing’). The most accurate map and accompanying description of the world, with the unlikely title of the ‘Book of Roger’ was produced in Sicily in 1154. It set the standard until the time of Mercator, three hundred years later.

The population of Sicily was still largely moslem, as it had been reconquered from the arabs less than a century previously. Palermo, the capital, had several hundred mosques. Like his grandson Frederick II whom we have already met, the Norman king Roger II of Sicily embraced arabic culture. He was dissatisfied with the maps available and in the arabic spirit of enquiry he decided to compile a better one. He commissioned a displaced aristocrat from al-Andalus, Muhammad al-Idrisi, to coordinate the project. Over fifteen years al-Idrisi interviewed travellers, compared their stories and finally put together an authoritative description of the known world, from the Canary Islands to Korea.


There was an engraved map on a large silver plate to accompany the book. In the conventions of the time, north is at the bottom of the map and south at the top. So Asia is on the left, Africa at the top and Europe at the bottom. Both the silver plate and the original book were destroyed in riots shortly after they were finished but many copies remain.

A copy of the book is online here, and it is exquisite (even if you don’t read arabic. The maps are over two pages, so each double-page image is a map and the single pages are text.)


There was  a smaller world map in the book, with Africa at the top and Europe at the bottom. It is said that this map inspired the Portuguese explorers to attempt to sail around Africa, as it is shown surrounded by sea.

There were other towering figures in this generation. Abbess Hildegard of Bingen wrote extensively, composed and corresponded. One of her correspondents was Bernard of Clairvaux, another influential person. He  joined the Benedictine order as a boy and wanted to reform the order, advocating a simpler life. He encouraged the establishment of monasteries in remote areas where they could be self-sufficient, living off the land. He was so driven that in his lifetime he was instrumental in the establishment of six hundred Cistercian monasteries (named after the first monastery he joined at Citeaux). He also campaigned to launch the second crusade to the Holy Land in this generation.

But the order Bernard attempted to reform had its own powerful individual. Peter the Venerable was the abbot of Cluny, the mother house of the previous wave of expansion and establishment of monasteries. He was an open-minded man who advocated understanding the saracens rather than trying to annihilate them. Especially as the second crusade turned out to be a disaster for the christians. He travelled to the Cluniac monastery of Santa Maria La Real in Najera, south of the Pyrenees, and from there to Toledo where the translation movement was in full flood. He persuaded two translators, Robert of Ketton (from a village near Rutland in present day England) and his friend Herman of Carinthia (a region in present-day Austria), to give up their attempts to translate Ptolemy’s Almagest and translate the Quran instead. Called the ‘Law of Mohammed the False Prophet’  the title shows his less-than-dispassionate approach to the subject. But at least the intention was there.

By a strange twist of fate, Robert of Ketton ended up as canon in the church at Tudela, not far from Najera. Tudela is the town from which rabbi Benjamin  set off on his travels in the following generation. So the two men almost certainly knew each other.

There was another English Robert participating in the translation movement at this time. Robert of Chester went to Segovia in al-Andalus. He translated the book that introduced Algebra to the latin north: al-Khwarizmi’s Liber algebrae et almucabola, written three centuries previously.


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