Philosophical Dictionary, by Voltaire


It is not as a physician, but as a patient, that I wish to say a word or two on fever. We cannot help now and then speaking of our enemies; and this one has been attacking me for more than twenty years; not Fréron himself has been more implacable.

I ask pardon of Sydenham, who defined fever to be “an effort of nature, laboring with all its power to expel the peccant matter.” We might thus define smallpox, measles, diarrhœa, vomitings, cutaneous eruptions, and twenty other diseases. But, if this physician defined ill, he practised well. He cured, because he had experience, and he knew how to wait.

Boerhaave says, in his “Aphorisms”: “A more frequent opposition, and an increased resistance about the capillary vessels, give an absolute idea of an acute fever. These are the words of a great master; but he sets out with acknowledging that the nature of fever is profoundly hidden.

He does not tell us what that secret principle is which develops itself at regular periods in intermittent fever — what that internal poison is, which, after the lapse of a day, is renewed — where that flame is, which dies and revives at stated moments.

We know fairly well that we are liable to fever after excess, or in unseasonable weather. We know that quinine, judiciously administered, will cure it. This is quite enough; the how we do not know.

Every animal that does not perish suddenly dies by fever. The fever seems to be the inevitable effect of the fluids that compose the blood, or that which is in the place of blood. The structure of every animal proves to natural philosophers that it must, at all times, have enjoyed a very short life.

Theologians have held, as have promulgated other opinions. It is not for us to examine this question. The philosophers and physicians have been right in sensu humano, and the theologians, in sensu divino. It is said in Deuteronomy, xxviii, 22, that if the Jews do not serve the law they shall be smitten “with a consumption, and with a fever, and with an inflammation, and with an extreme burning.” It is only in Deuteronomy, and in Molière’s “Physician in Spite of Himself,” that people have been threatened with fever.

It seems impossible that fever should not be an accident natural to an animate body, in which so many fluids circulate; just as it is impossible for an animate body not to be crushed by the falling of a rock.

Blood makes life; it furnishes the viscera, the limbs, the skin, the very extremities of the hairs and nails with the fluids, the humors proper for them.

This blood, by which the animal has life, is formed by the chyle. During pregnancy this chyle is transmitted from the uterus to the child, and, after the child is born, the milk of the nurse produces this same chyle. The greater diversity of aliments it afterwards receives, the more the chyle is liable to be soured. This alone forming the blood, and this blood, composed of so many different humors so subject to corruption, circulating through the whole human body more than five hundred and fifty times in twenty-four hours, with the rapidity of a torrent, it is not only astonishing that fever is not more frequent, it is astonishing that man lives. In every articulation, in every gland, in every passage, there is danger of death; but there are also as many succors as there are dangers. Almost every membrane extends or contracts as occasion requires. All the veins have sluices which open and shut, giving passage to the blood and preventing a return, by which the machine would be destroyed. The blood, rushing through all these canals, purifies itself. It is a river that carries with it a thousand impurities; it discharges itself by perspiration, by transpiration, by all the secretions. Fever is itself a succor; it is a rectification when it does not kill.

Man, by his reason, accelerates the cure by administering bitters, and, above all, by regimen. This reason is an oar with which he may row for some time on the sea of the world when disease does not swallow him up.

It is asked: How is it that nature has abandoned the animals, her work, to so many horrible diseases, almost always accompanied by fever? How and why is it that so many disorders exist with so much order, formation, and destruction everywhere, side by side? This is a difficulty that often gives me a fever, but I beg you will read the letters of Memmius. Then, perhaps, you will be inclined to suspect that the incomprehensible artificer of vegetables, animals, and worlds, having made all for the best, could not have made anything better.

Last updated Sunday, March 27, 2016 at 12:01