‘Again, the muscles of the arms, legs, and thighs contain vessels full of humours; and just as the belly has within it viscera containing nourishment, so the muscles of arms, legs, and thighs have both vessels and the [contained] humours which preserve man’s strength.... But when a man runs or walks quickly, the nerves about the knees and the venules in the knees become distended. And since they are united with the vessels of the legs, which are numerous and intercommunicate in a net-​like manner, they conduct the fatigue to the vessels of the liver, and thus they reach the vessels of the brain, and so send the fatigue throughout the body. But the vessels from the reins pass rather to the left leg than to the right, because the right leg gets its strength more from the heat of the liver. And the vessels of the right leg ascend as far as the renal and kindred vessels, and these latter vessels unite with those of the kidney. And the liver warms the reins which lie in the fatness derived from the humours....

‘The humours in man are distributed in just measure. But when they affect the veins of the liver, his humidity is decreased and also the humidity of the chest is attenuated; so that thus dried, he falls into disease of such a nature that the phlegm is dry and toxic and ascends to the brain. There it produces headache and pain in the eyes and wasting of the marrow, and thus if the moon is in default he may develop the falling evil [epilepsy].

‘The humidity also which is in the umbilicus is dispersed by the same humours, and turned into dryness and hardness, so that the flesh becomes ulcerated and scabby as though he were leprous, if indeed he do not actually become so. And the vessels of his testicles, being adversely affected by these humours, similarly disturb the other vessels, so that the proper humidity is dried up within them; and thus, the humours being withdrawn, impetigos may arise ... and the marrow of the bones and the vessels of the flesh are dried up, and so the man becomes chronically ill, dragging out his days in languor.

‘But sometimes the humours affect breast and liver ... so that various foolish thoughts arise ... and they ascend to the brain and infect it and again descend to the stomach and generate fevers there, so that the man is long sick. Yet again they vex the minor vessels of the ear with superfluity of phlegm; or with the same phlegm they infect the vessels of the lung, so that he coughs and can scarce breathe; and the phlegm may pass thence into the vessels of the heart and give him pain there, or the pain may pass into the side, exciting pleurisy; under such circumstances also, the moon being in defect, the man may lapse into the falling sickness.’[106]

Sometimes Hildegard’s anatomical ideas can be paralleled among her contemporaries. Thus the following passage on the relationship of the planets to the brain is well illustrated by a diagram of Herrade de Landsberg.

Fig. 9. From Herrade de Landsberg’s Hortus deliciarum, after Straub and Keller’s reproduction.[107]