Chapter 2

The dogmatists hold that there is no doubt that sense and experi­ence are the root and principle of all sciences and arts, but these must be subject to the instruments of thought. They say that the rules of medicine and of other arts must be derived through thought and analogy; that is, the determination of unknown things through things which are known. It is through the use of thought and analogy that the various natures and constitutions may be known, and through which the faculties which are the cause of changes in the body may also be known.

Causes of changes in the body are of two types. One is that which necessarily results in alteration: such as climate, movement and rest, food and drink, sleep and wakefulness, and constipation and looseness, as well as mental occurrences such as sorrow or happiness, anger or joy. The second type of .cause is that which results in a change in the body without that change being necessary: such as the change which appears as the result of the blow of a sword, the attack of a wild animal, or burns inflicted on the body.

It is also necessary to know the type of illness which the physician intends to treat, for if it is not known it will not be possible to take it away from the body. Finally, one must know the extent of the illness in order that the type of treatment be determined. The extent will vary in accordance with the following factors: the bodily strength of the patient, age, temperament, the season in which the illness appears, the weather on the day it appears, the type of city the patient lives in, and his habits and profession.

The difference between these two sects is that when a patient comes to an empiricist he refers to his previous experience of persons who have had the same type of illness to the same degree, and who are of similar age and temperament. Then he prescribes the same medicine which proved effective in the past. The analogist will, however, on the basis of the same evidence ‑ that is age, temperament, habits, and residence ‑ envisage a general rule with regard to each type of sickness, and when he is presented with a new case will refer to that rule.