From 1798 onwards, Geoffroy and Cuvier had still been close friends, working at the Paris museum just after the revolution when excitement was in the air. They worked long and hard and mixed with intellectual and political society. Geoffroy even left a note for Cuvier when he went off to Egypt with Napoleon’s academic entourage: “Goodbye my friend, love me always. Do not cease to consider me as a brother.”

They carried on  working together on the same projects, then Cuvier moved on to make his own precise reconstructions from fossil bones and Geoffroy made more comparisons of whole groups of living things. Gradually they grew further apart, encouraged by their different personalities and of course these determined what they were good and bad at. Cuvier always made careful and precise dissections; he drew very accurately and beautifully, but was always very controlled, tight-lipped and calculating. His life was ordered and tidy, run with strict rules and precision. In comparison, Geoffroy’s work was more outward-looking, more concerned with the whole picture, looking for fresh light to solve a problem. This also meant that he could be a reckless dilettante, spontaneous, looking for metaphors and models that might bring things together. In the new freedom of the Paris museum in the 1810s and 20s there was space for both attitudes, and the other scientists there enjoyed the contrasts of the growing disparity. Slowly, the two men became well known as intellectual opponents, students taking sides proudly and other biologists eagerly waiting for the next publication from one side or the other.

They principally differed in accounting for how the bodies of different species were formed, whether they all developed along the same pathway, one limb being equivalent in different species, or whether they comprised separate groups of each sort. Cuvier was all for fixed functions and followed the old cliché that people climb mountains because they are there. Since there are many different kinds of mountains each appealing to different structured limbs and lungs, so there are different organs adapted to the different conditions and functions. On the other hand, Geoffroy argued that “there is, philosophically speaking, only a single animal”, variations of the same model or blue-print. There was a central column with a varying number of appendages whose use also varied: primates walked on just two, other mammals used four, and centipedes many more.

In 1830 two students gave a lecture about this model to the Academie des Sciences suggesting that a squid, a kind of mollusc, conformed to Geoffroy’s standard vertebrate model, their back-bone bending back at the middle so the base of the spine lined up with the neck. Cuvier was infuriated at their suggestion that molluscs were anything like vertebrates, and of course, Geoffroy was delighted. As a form of post-revolutionary duel the two agreed to debate their differences at the Academie every Monday afternoon until one withdrew.

The youngest, Geoffroy, opened the first encounter at noon on February 15 1830 with a flourish, supporting the students’ interpretation of parts of the squid’s spinal column as equivalent to vertebrae that varied according to guidelines of the blueprint. It was not unlike the model for leaf variation that Goethe had proposed for plants. The next week it was Cuvier’s turn. Some organs may have looked similar but they had quite different arrangements “often constructed in a different manner, and accompanied by several other organs that vertebrates do not possess.” Cuvier’s functionalist argument was impressive.

One of the students later wrote: “I cannot find words to express how devastated I am that our Memoir has given rise to disputes. We could scarcely believe that anyone could draw such exaggerated consequences from a single, simple consideration on the organization of molluscs.”  But the debate went on, each protagonist making wider generalizations from more examples of their work, exaggerating to make their points.

Further debates didn’t improve the chances of either argument. Cuvier always returned to his fixed anatomy for each species, stable forms suddenly coming and suddenly going, but never changing. Geoffroy was all for change, stimulated by the environment, one species changing into another. In the fourth debate he illustrated his progression with some examples: he cited a species of marine lizard found as a fossil in the chalk deposits near Paris, and suggested it had changed into a crocodile, then that into a giant mammal, and finally into an extinct paleotherium. Even then it sounded like a stupid idea and to make matters worse he had no new evidence, just a very large number of missing links. Even the ages of the fossils were in the wrong sequence and the anatomical affinities were confused. Much to Cuvier’s surprise and pleasure Geoffroy went on with even more bad examples. Fish turned into cephalopods, and he linked the lowest vertebrates to the highest mollusks.

The latest, 2013, ideas about the ancestry of some of the major vertebrate groups is shown in two diagrams.

Not surprisingly, the fifth debate on March 8^th had to be cancelled because Geoffroy was ill and the next week Cuvier refused to attend to make things even. The crowd of spectators was furious. Geoffroy took Cuvier head-on about the evolution of crocodiles – whether they had evolved through environmental revolution or internal reorganization. Like Lamarck he expected an uninterrupted path of generation, a slow merging from the simple to more complex in very similar environments. Instead of Cuvier’s extinctions at every revolution, Geoffroy suggested that the environment caused the internal changes directly.

By the sixth week the debate began to run out of steam. A disappointed man from the crowd even asked whether the speaker agreed with Goethe that he was: “not anti-Christian, nor un-Christian, but most decidedly not Christian”. Geoffroy announced that he would not continue in this “pit, applauding the outrageous comedies of Aristophanes.” The majority verdict was that there was no winner, a conclusion summed-up by Goethe who thought that “the more vitally these two [directions] of the mind are related, like inhaling and exhaling, the better will be the outlook for the sciences and their friends.” Unfortunately, not many people heard him then, and fewer read his scientific work since.

     Goethe’s frustrated character Faust was damned for thinking that humans could learn the tools of God’s trade, be able to refine the crudity of nature, and separate the wheat from the chaff. Human knowledge was certainly moving fast during the 1820s and the German capital was almost as exciting a place as Paris.

  The idealist and philosopher Georg Hegel (1770-1831) lectured there at the university in Berlin, saying that beneath the anarchy and chaos of human affairs, the spirit of reason was at work, not only in those contemporary turbulent times but for long before, and doubtless into the future as well. With this strong sense of optimism, the story of life on earth was at a changing point, science taking over the role of driving force, replacing the insecurity and fear from the myths that had held sway. It was a new age with a new knowledge, but using the strong spirit of reason. Hegel believed that the history of materialism began with the ordering of early life on earth, then reading through the stories of the bible, and then passing through the methods of science to a new level. Could this journey mean that the science laboratory was to subsume the church?

Hegel might have been surprised to find support from a London lawyer: “England is more parson-ridden than any country in Europe except Spain”. Despite this over-emphatic opinion, Charles Lyell was determined to “free the science from Moses.” Not only was he thinking of his own teacher at Oxford in 1820 but of the attitude across so much of society in Britain at the time. The old ways of thinking, the old habits of living just wouldn’t go away gradually and without a fight. In particular, he thought that Professor Buckland, who still commanded a big following, was thinking in one century and living in another.