1543 has a good claim to be the year when modern science began. It saw the publication of Copernicus’ On the Revolutions of the Heavenly Spheres (see below p. 8) and of Andreas Vesalius’ On the Fabric of the Human Body (generally known by its Latin title, the Fabrica). The text of this book – the foundation of modern anatomy – was accompanied by magnificent illustrations, designed by artists of the school of Titian, and cut on fine pearwood by Venetian block-cutters, which show the arteries, veins, muscles and nerves of the human body.

A well-off Belgian doctor’s son, Vesalius (1514–64) had been given the best medical education available, studying at Louvain, Paris and Padua, where he became Professor of Anatomy at the age of 23. His mission was to rescue anatomy from the errors of the ancient Greek physician Galen, who still dominated medicine in the sixteenth century. Galen had had to depend on animal corpses for his knowledge of anatomy, and the prejudice against cutting up human bodies was still strong at the start of Vesalius’ career. At Louvain, wishing to construct a human skeleton, he stole the remains of a malefactor from a gibbet outside the city. In order to satisfy his curiosity about the fluid in the pericardium, he contrived to be present when a criminal was quartered alive and (he recalls) carried off for study ‘the still-pulsating heart with the lung and the rest of the viscera’. Once he was established in Padua, the magistrates supplied him with corpses fresh from the gallows, and executions were timed to coincide with his anatomy lessons.

Unlike previous professors he did not sit aloof on his throne while a barber surgeon cut up the cadaver, but carried out the dissection himself. The title page of the Fabrica – as if to emphasize masculine conquest of ‘Mother Nature’ – shows him handling the abdominal organs of a naked, cut-open woman, surrounded by tiers of eager male spectators. The woman, Vesalius records, had tried to cheat the gallows by declaring herself pregnant.

By chance an eyewitness account of Vesalius’ first public anatomy classes survives, written by a German student, Baldasar Heseler. Held in Bologna in 1540, the classes covered the dissection of three human corpses, but the last class was on a living dog. The question which puzzles the students in this extract had already been answered by Vesalius at the end of his previous lecture, where he pointed out that it was when the heart contracted that it pumped blood into the pulmonary artery – so evidently the students had not been listening.

Finally, he took a dog (which was now the fifth or perhaps the sixth killed in our anatomy). He bound it with ropes to a small beam so that it could not move, similarly he tied his jaws so that it could not bite. Here, Domini, he said, you will see in this living dog the function of the nervi reversivi, and you will hear how the dog will bark as long as these nerves are not injured. I shall cut off one nerve, and half of the voice will disappear, then I shall cut the other nerve, and the voice will no longer be heard. When he had opened the dog, he quickly found the nervi reversivi around the arteries, and all happened as he said. The bark of the dog disappeared when he had by turn cut off the nervi reversivi, and only the breathing remained. But, he said, it can still quite well bite, do not let its jaws free, hold it strongly. Finally, he said, I shall proceed to the heart, so that you shall see its movement, and feel its warmth, and so that you shall here around the ilium feel the pulse with one hand, and with the other the movement of the heart. And please, tell me, what its movement is, whether the arteries are compressed when the heart is dilated, or whether they in the same time also have the same movement as the heart. I saw how the heart of the dog bounded upwards, and when it no longer moved, the dog instantly died. Those mad Italians pulled the dog at all sides so that nobody could really feel these two movements. But some students asked Vesalius what the true fact about these movements was, what he himself thought, whether the arteries followed the movement of the heart, or whether they had a movement different from that of the heart. Vesalius answered: I do not want to give my opinion, please do feel yourselves with your own hands and trust them. He was said always to be so little communicative.