THEIR EXPLANATION OF DISEASE AS DEMONIACAL POSSESSION IS WRONG.
They also pride themselves on expelling diseases. If this were done through temperance, by a well regulated life, as do the philosophers, this claim might be respected. But they insist that diseases are demons, which they can expel by their words, and they boast of this in order to achieve reputation among the common people, that is always inclined to stand in awe of magic. They could not persuade rational individuals that diseases do not have natural causes, such as fatigue, satiety, lack of food, corruption, or some change depending on an interior or exterior principle. This is proved by the nature of diseases. Sometimes a disease is expelled by moving the bowels, or by the administration of some potion; diet and bleeding are also often resorted to. Is this because the demon is hungry, or the potion destroys him? When a person is healed on the spot, the demon either remains or departs. If he remain, how does his presence not hinder recovery? If he depart, why? What has happened to him? Was he fed by the disease? In this case, the disease was something different from the demon. If he enter without any cause for the disease, why is the individual into whose body he enters not always sick? If he enter into a body that contains already a natural cause of disease, how far does he contribute to the disease? The natural cause is sufficient to produce the disease. It would be ridiculous to suppose that the disease would have a cause, but that, as soon as this cause is active there would be a demon ready to come and assist it.