Page:Popular Science Monthly Volume 75.djvu/9



COMMON observations early indicated that individuals of all animal species, and of the human species especially, were very unequally subject to disease. This elementary fact is impressed every day upon the thoughtful and has been, from the earliest times, the object of much ingenious speculation. Even to-day, and in spite of the acquisition of a wealth of new facts in physiology and pathology, we are not able to define fully the conditions that make for or against disease. However, the new knowledge which has been acquired enables us to see much more deeply and clearly into the complex mechanisms of disease than could be seen half a century ago; but unfortunately our insight has not been strengthened as regards all diseases, but almost exclusively in relation to the infectious diseases. In respect to the other class, or noninfectious or chronic diseases, among which are Bright's disease, vascular disease, malignant tumors, the gains in fundamental knowledge are far less great.

It may be axiomatic to state that all actual progress in unraveling the complicated conditions of disease depends upon precise knowledge of its underlying causes; and yet in an age in which comparative ignorance still requires that a certain amount of practise shall be empirical, it is well to bear in mind this notion, so that what is undertaken through knowledge may be kept distinct from what is adventured through ignorance. It has been to the lasting credit of the medical profession of an early period, when actual knowledge of the underlying causes of disease had not, and in the then state of development