It happens that certain men suffer diverse illnesses. This comes from the phlegm which is superabundant within them. For if man had remained in paradise, he would not have had the flegmata within his body, from which many evils proceed, but his flesh would been whole and without dark humor [livor]. However, because he consented to evil and relinquished good, he was made into a likeness of the earth, which produces good and useful herbs, as well as bad and useless ones, and which has in itself both good and evil moistures.
From tasting evil, the blood of the sons of Adam was turned into the poison of semen, out of which the sons of man are begotten. And therefore their flesh is ulcerated and permeable [to disease]. These sores and openings create a certain storm and smoky moisture in men, from which the flegmata arise and coagulate, which then introduce diverse infirmities to the human body. All this arose from the first evil, which man began at the start, because if Adam had remained in paradise, he would have had the sweetest health, and the best dwelling-place, just as the strongest balsam emits the best odor; but on the contrary, man now has within himself poison and phlegm and diverse illnesses.
— From Hildegard of Bingen's medical writings: Causes and CuresPublic Domainbooks.google.com