applied the learning of Aristotle to his practice of medicine. Man, he said, is but matter containing certain properties. If these properties be in correct proportion, well and good; but if the balance be upset, sickness results. The therapeutics of Galen consisted, therefore, in restoring the lost property. If the patient had a chill, he put him in a warm bath; if he had a fever, he put him in a cold bath.
Van Helmont, whose work belongs chiefly to the first half of the seventeenth century, tells us of the existence of an Archæus, and in this theory he was supported by Paracelsus. The Archæus was a spirit which had its abode in the stomach of man. If the Archæus were well nourished, he was pleased and happy; but if anything disagreeable reached him, he made his displeasure painfully evident, and if something were not done to appease his anger, he betook himself off, and the man was dead.
Our present views are entirely different. Properties are not separable from matter. Properties are inherent in matter. Ujjon this knowledge our modern opinions are based. We have spoken of a belief that life depended on a property—a "vital force." A "force" may be defined as something that can not be explained. The laws of gravitation stand as Newton left them, but what the force of gravitation is no man can say. Hence, the expression "vital force" was but a confession of ignorance. No, there is no such thing as a "vital force." There are in living Nature and in the inanimate world the same materials, ruled in both cases by the same natural chemical and physical laws, only the conditions in living Nature are different from the conditions in the inanimate, and consequently the phenomena observed are likewise different.
Let us now look at some of the discoveries which have caused us to accept this material view of life.
Harvey, in 1616, first taught the true doctrine regarding the circulation of the blood, and compared the heart to a pump.
Scheiner, a Jesuit priest, declared the action of the eye to be like that of a camera obscura, the lens of the eye acting to form a picture on a background.
Keppler developed the theory of spectacles.
Borelli explained how the mechanism of breathing was due to the elasticity of the lungs and to the muscles acting as power upon levers—the ribs.
Lavoisier showed that animal heat was due to the decomposition of higher chemical compounds of the food eaten, just as the heat of the candle is produced by the combustion of its constituents.
All these facts are easily seen to be but followings after Nature's laws. Chemistry brings many proofs confirming the doc-