Page:The Hunterian oration, for the year 1819.djvu/11

Rh nothing but error and pernicious notions. It is a very great but very common misemployment ot our reasoning powers, to draw inferences from facts belonging to different subjects, which are incommensurate with one another. Such irrelevant facts have been often designated by the whimsical and contradictory expression of false facts. We are indeed sometimes induced to reason from analogy, but then the similarity of the facts is so precise, as to warrant us in believing that the subjects, concerning which we thus comparatively reason, are essentially alike.

Now without any knowledge of anatomy, or the animal economy, persons of the medical profession, by drawing inferences from mixed facts, might suppose, that a fire was kindled throughout the body to warm and cherish it, which, if in excess, might set our juices into fermentation, and thus produce partial or general disorder; they might suppose, that there were elements in the body, which ought to be combined in definite proportions, and that different diseases might result from the excess or deficiency