The heart is surrounded by a firm and nervous membrane, like a little house in which it is placed as in a tabernacle to defend it from accidents. This capsule is very dilated, that the heart in its dilations and movement may not be impeded thereby, and therefore nature made this capsule so that it should contain a certain dewy moisture with which the heart is bathed and moistened so that in its continual movement it should not become dry. For when this water be dried up, then the heart itself is desiccated, and emaciates and dries up all the body.

The description of the heart follows Mondino closely. Occasionally a phrase or two is reminiscent of Mondeville. The trite conception of the heart as a king in its necessarily central position was very frequently repeated by writers in the Middle Ages. To Harvey, who had a certain mediaeval element in his mentality, it seems to have appealed, and he used it in his Prelectiones Anatomiae,[202] and chose it to introduce his great work on the circulation of the blood.[203] The heart was similarly described as ‘flame-​shaped’, because it was regarded as the source of animal heat. The idea that it is the first to live and the last to die comes from Aristotle.[204] The bone in the heart also comes from Aristotle.[205] The idea was quite familiar to mediaeval anatomists, who frequently endeavoured to identify the bone with the firm tissue around the orifices of the aorta and pulmonary artery. The reader may be reminded that a true ‘os cordis’ is in fact to be found in some mammalia.

Mondino, followed by Manfredi, describes the action of the heart and blood-​vessels mainly according to the views of Galen, but without any very clear or connected statement. The ‘third ventricle’ especially has its origin in a misunderstanding.

This mythical structure is an attempt to combine the views of Aristotle and of Galen. Aristotle, who probably never dissected a human body, derived his anatomical conceptions largely from cold-​blooded animals, in some of which the heart is provided with three cavities. He considered that the heart had three chambers, the largest being on the right, the smallest on the left, and one of intermediate size between the two. As far as they can be identified, the largest was the right ventricle plus the right auricle, the smallest or left chamber was the left auricle, while the intermediate cavity appears to have been the left ventricle.[206]

Fig. 21. THE HEART
From the Roncioni MS. (Pisa 99) after Sudhoff.