The Greatest Benefit to Mankind. Roy Porter

flayed and horrible to behold’, it was after 1506 that Leonardo made his main anatomical contributions, devoting his attention to embryonic development, the muscles, and the nervous, vascular, respiratory and urino-genital systems. The vessels and respiratory passages were compared to the branching of trees and river valleys, and the workings of the heart explained in terms of hydrodynamics and mechanics. Leonardo executed about 750 anatomical drawings, which in some respects are superior to those in Vesalius’s Fabrica (1543), yet his thinking remained traditional. He continued to accept the Galenic doctrine that blood passed between the ventricles through invisible pores in the septum; and his drawings of the embryo were set within a ‘traditional’ womb. His career reflects the new involvement of artists with anatomy, though his work had no influence on contemporary medicine, since none of his anatomical manuscripts was published until the late eighteenth century.

      As well as artists, medical men also anatomized. Among Renaissance anatomists the desire to see for oneself (the literal meaning of ‘autopsy’) arose from a variety of traditions. Berengario da Carpi (c. 1460–1530) studied at Bologna, the cradle of dissection, and in 1502 became lecturer in surgery there. He made the basis for his lectures the Anatomy of his Bolognese predecessor, Mondino, and his Introduction follows earlier procedures for public dissection. Berengario was no slavish imitator. While often using Galen to disprove Mondino, he was prepared to criticize him on the basis of personal observations, denying the existence in humans of Galen’s rete mirabile, that ‘marvellous network’ of blood vessels supposedly lying at the base of the brain (it is found in some animals but not in humans). Insisting on the need for frequent dissections, including humans, he gained a knowledge of female internal anatomy on the basis of postmortem examinations, including one of an executed pregnant woman.

      The earliest truly Greek anatomical text was that of Alessandro Benedetti (d. 1512), who lived for sixteen years in Greece and Crete before returning to Padua in 1490 as professor of practical anatomy. In his Historia corporis humani; sive anatomice (1502) [The Account of the Human Body: Or Anatomy], the Greek anatomice in the title highlighted his hellenism. As a good humanist, Benedetti, like Leoniceno, weeded out Arabic terminology and self-consciously used Greek anatomical terms. Though his book was philological rather than substantive, it did provide an account of a well-ordered anatomy theatre.

      Humanist anatomy was given a boost by the discovery of the first part of Galen’s On Anatomical Procedures (his treatise on how to carry out a dissection) translated into Latin by Guinther von Andernach in 1531. Mondino had started with the internal organs, since these putrefied first. His procedures were rejected by humanists in favour of Galen, who had begun in a more logical fashion with the bones – they were like the walls of houses, he wrote, everything else took shape from the skeleton – next proceeding to the muscles, nerves, veins and arteries, before reaching the cavities of the belly, the chest and the brain, and the internal organs.

      But if Galen’s dissection strategy was more rational and the quality of his descriptions superior, its flaw was that it was animal not human. A challenge was thus thrown down to anatomists to outdo the master through hands-on investigation of the human corpse. The Liber introductorius anatomiae (1536) [Introductory Book of Anatomy] of the Venetian physician Niccolò Massa (c. 1485–1569) scolded those who pronounced on anatomy without having applied the knife to the things they wrote about.

      By the 1520s increasing numbers of anatomical texts were being published, and Johannes Dryander (1500–60), professor of medicine at Marburg, carried out some of the first public dissections in Germany, writing these up in a treatise on the anatomy of the head. Andreas Vesalius (1514–64), however, restored Galenic anatomy in such a way as to transcend it. A true Galenic anatomist, in the sense of following the master’s advice to see for oneself, Vesalius also presented himself in his De humani corporis fabrica (1543) [On the Fabric of the Human Body] as a critic who had no compunction about exposing Galen’s errors: ‘How much has been attributed to Galen, easily leader of the professors of dissection, by those physicians and anatomists who have followed him, and often against reason!’

      Born Andreas van Wesele in Brussels, where his father was pharmacist to Emperor Charles V, Vesalius learned Latin and Greek and enrolled in the Paris Faculty of Medicine, studying under the conservative humanist Sylvius, then Galen’s great champion. (In later years Sylvius became a scourge of Vesalius, wittily calling him vesanus: madman.) Vesalius learnt his dissecting skills from Guinther von Andernach, and when in 1536 war forced him to flee Paris, he returned to Louvain where he introduced dissection. He showed his anatomical zeal by robbing a wayside gibbet, smuggling the bones back home and reconstructing the skeleton.

      In 1537 he moved to Padua, where he made his anatomical name. Dissection had previously been demonstrated there by surgeons, and had never been mandatory for physicians. The rediscovery of Galen’s On Anatomical Procedures and the wider dissemination of his On the Use of Parts meant that humanists were beating the drum for the subject, and the appointment of the young physician was one consequence. Vesalius’s Tabulae anatomicae sex (1538) [Six Anatomical Pictures] were among the first anatomical illustrations specifically designed for students. The first three sheets were drawn by Vesalius himself and represented the liver and its blood vessels, together with the male and female reproductive organs, the venous and the arterial system. He was still viewing the body through Galenic eyes: despite Berengario, he drew the rete mirabile; the liver was still five-lobed, and the heart an ape’s.

      Thereafter Vesalius grew more critical. Familiarity with human anatomy drove him to the unsettling conclusion that Galen had dissected only animals, and forced him to see that animal anatomy was no substitute for human. He now began to challenge the master on points of detail: for instance, the lower jaw comprised a single bone not two, as Galen, relying on animals, had stated. Evidently, human anatomy had to be learned from dead bodies not dead languages.

      In 1539 he acquired a larger supply of cadavers of executed criminals and worked on his great masterpiece, the De humani corporis fabrica. Finishing it in 1542, he took it to Basel where the press of Joannes Oporinus published it in 1543 as one of the pearls of Renaissance printing. It presents exact descriptions of the skeleton and muscles, the nervous system, blood vessels and viscera. Though it contains no shattering discoveries, it marks a watershed in the medical understanding of bodily structures, for Vesalius interrogated Galen by reference to the human corpse. Others had criticized odds and ends of Galenic anatomy, but Vesalius was the first to do this systematically. The Fabrica gained immensely from the contribution of the artist, Jan Stephan van Calcar (1499–c. 1546), also from the Netherlands, who provided the text with technically accurate drawings displaying the dissected body in graceful lifelike poses. The work also enunciated clear methodological principles: the anatomist-lecturer must perform the dissection himself, the eye was preferable to authority, and anatomy was the skeleton key to medicine.

      Book I of the Fabrica began in Galenic fashion with the bones rather than the internal organs. Various Galenic lapses were corrected: for example, the human sternum has three, not seven, segments. Book II dealt with the muscles and included the famous suite of illustrations showing ‘muscle-men’ at different stages of corporeal ‘undress’. Book III, on the vascular system, was less accurate because Vesalius still based his descriptions partly on animal material. Book IV described the nervous system, following the Galenic classification of the cranial nerves into seven pairs.

      Book V dealt with the abdominal and reproductive organs, where he corrected Galen’s belief in the five-lobed human liver. He nevertheless still accepted the Galenic physiological tenet that the liver produced blood from chyle, while denying that the vena cava originated in the liver – an observation which, had Vesalius been more physiologically-minded, might have begun the erosion of the Galenic belief in two distinct vascular systems, the venous originating in the liver and the arterial stemming from the heart.

      Book VI was devoted to the thorax. Examining the heart, Vesalius cast doubt on the permeability of the interventricular septum: ‘We are driven to wonder at the handiwork of the Almighty by means of which the blood sweats from the right into the left ventricle through passages which escape the human vision.’ In the second edition (1555), this implicit denial of the septum’s permeability