The Canon of Medicine (Canon Medicinae), Vol. II

the heat is recalled, the heart is heated to the maximum degree, because the external arteries are cooled and cannot be sufficiently dilated. Otherwise, the pulses would necessarily be large, unless this coldness of the external parts obstructed them. In those who are dying, however, the situation is different. The expiration becomes cold because the innate heat has already wasted away, and the vital spirits have been cooled; not only these, but also the humors, the heart, and everything around the heart. Thus, in our judgment, the question regarding the genus of fever is vain. Furthermore, regarding the actions, although some believe all and others believe not all are injured by fever, it should not be thought that they disagree so much among themselves. Truly, it is necessary for all other actions to consent to the action of the heart; yet, it is not necessary that all be affected in a way that can be discerned by the senses. Even if not all vital, natural, and animal actions are injured specifically or particularly, nevertheless, out of all the types of actions, some are injured, whether animal, vital, or natural; above all, however, the vital ones. Having noted these things, therefore, we do not labor over the fact that some approve of the theory of fever handed down by Galen, while others approve of others. It certainly seems to us that the theory Avicenna writes in this place is somewhat more complete, as it explains everything together that Galen taught sporadically. For he also mentions the instruments themselves, namely the veins and arteries, without the help of which a fever cannot be ignited. Even if the cords—the parts nearest to them—can also become heated by contact, and those joined to these in turn even to the extremities, nevertheless, it cannot happen so readily. It seems there is no other reason Chapter 6. (a fact also noted by Alexander of Aphrodisias in his treatise on fevers) that the heat which is against nature is imparted to the whole body, other than through the veins and arteries, through the spirits and blood, by which it is imparted naturally. The author adds one thing to the theory of fever, which Galen also notes, that fever is harmful to natural operations; by "natural," he understands those actions which are in accordance with nature. But Averroes says that not only actions but also passions are affected. Yet, these do not disagree among themselves; for by "actions," they understand not only those that are truly actions, but also those that are called παθήματα passions/sufferings. Likewise, in the definition of disease, by "actions," not only true actions are understood, but also passions and uses.

And there are some men, etc. He brings forward the opinion of some who would assert that fever is in one case a disease and in another a symptom, and he seems to explode this view. They therefore thought that some person was opposing Galen, who in Ad Glauconem and the 4th Aphorism calls fevers sometimes symptoms and sometimes diseases. Although he himself, in the book On the Differences of Diseases, asserts that those who think this about fever are to be blamed if it happens after a sensible affection of some member, to be considered an accident, otherwise a sickness. But as far as this controversy is concerned, it is clear from the places already cited, in Ad Glauconem and in the Aphorisms, that fever is in one instance an accident and in another a disease, according to Galen's opinion. Nor does the authority objected to in the latter place Chapter 3 & 4. Comment 66. Chapter 5. stand in the way, since he does not condemn them there because they want fever to be sometimes an accident and sometimes a disease, but because, while they held the heresy that "a damaged action is a disease," they did not keep their own hypothesis; for they called a convulsion—which is a damaged action—sometimes by the name of a disease and sometimes of a symptom, and thus they felt the same about fever. If it happens after a sensible affection of some member, it is an accident; otherwise, it is a disease. Thus, Galen does not condemn the thing itself, but their inconsistency. But truly, we will explain in a few words what we feel regarding whether fever is truly given as a symptom and as a disease. If that is a symptom which perpetually follows diseases without a medium, it cannot be denied that fevers which succeed a bubo are symptoms; indeed (which one might perhaps admire), all fevers resulting from obstruction are symptoms because they follow other diseases. Yet, since they follow neither a disease nor a cause of disease, they primarily injure the actions, and must always be placed in the category of diseases. But for the sake of the cure, although it does not befit a physician to contend longer over this matter, as our author also advises, it seems to matter not a little to note what happens first and what in the second place, because diseases are often conjoined. If a bubo was the cause of the fever, the fever itself will be removed by the cure of the bubo, but not if a bubo supervenes upon a feverish patient. If fever arrives from obstruction, it is not cured unless the obstruction is removed; but if the obstructions occurred after the fever began, either because of poorly performed digestion or because of the regimen, the method of curing will be different. Thus, for the sake of the cure, fever sometimes has the nature of a symptom and sometimes of a disease, although it is always a disease. Just as pains, which are always symptoms, sometimes take on the nature of diseases and morbific causes. We believe that our author seems to disapprove of this opinion because of the opposing essence of fever, not if you look to the cure or to other affections which fever follows without a medium, which are sometimes the cause and sometimes the diseases themselves.

3 Since because everything that is in the body, etc. He emulates Galen in the first book On the Differences of Fevers, where he commends Hippocrates for explaining the essential differences of fevers most briefly. He calls those most proper which are taken from the triple material in which the fever is ignited. Avicenna says this division is close to the division occurring through differences, as if he meant this division to be as it were of a genus into species, though not, as some understand, that he thinks heat, hectic, ephemeral, and putrid fevers differ from each other by the species of fever; rather, since the heat is of the same genus, different species emanate from its differently characterized subjects—unless you prefer to call these differences rather than species, which is not something physicians labor much over. For this author did not ignore that these are called substantial differences by Galen, because they are in a way taken from the nature of the specific heat, which is a quality and therefore in a subject. However, he did not say it was absolutely through differences, but through a mode close to division by differences, because these are not true specific differences of fever, as they arise from the subject of the heat, not from the essence of the heat itself, although perhaps no other difference of fevers is closer than this one, which is taken from the material.

On preparations for fevers. Chapter 2.

Some have said that bodies more vehemently prepared for fevers are hot and moist bodies: and properly when the humidity is stronger than the heat, and these indeed are those of foul sweat, and urine, and excretion. And hot and dry bodies again are prepared for a B. acute. hot fevers: and they begin more as ephemeral, then they hasten to putrefaction and adustion: and sometimes they cause one to fall into a hectic fever, and those two follow, which are equalized in humidity and dryness, and the heat dominates, and these are of the genus of those in which a fever of hot vapor begins, then it is changed to a fever of the humor. Afterwards, those in which heat and cold are equalized, and humidity is multiplied, and to these indeed fevers of putrefaction occur, mostly beginning, and cold and moist bodies, and cold and dry bodies, are the bodies furthest from fevers, and properly from ephemeral fever.

The question in this place is, which bodies are more prompt to be seized by fevers? Hence absolutely (although of others