The difficulty is to get men to the thinking level which compels the application of scientific truths. Protagoras, that "mighty-wise man," as Socrates called him, who was responsible for the aphorism that man is the measure of all things, would have been the first to recognize the folly of this standard for the people at large. But we have gradually reached a stage in which knowledge is translated into action, made helpful for suffering humanity, just as the great discoveries in physics and chemistry have been made useful in the advance of civilization.

We have traced medicine through a series of upward steps-- a primitive stage, in which it emerged from magic and religion into an empirical art, as seen among the Egyptians and Babylonians; a stage in which the natural character of disease was recognized and the importance of its study as a phenomenon of nature was announced; a stage in which the structure and functions of the human body were worked out; a stage in which the clinical and anatomical features of disease were determined; a stage in which the causes of disorders were profitably studied, and a final stage, into which we have just entered, the application of the knowledge for their prevention. Science has completely changed man's attitude towards disease.

Take a recent concrete illustration. A couple of years ago in Philadelphia and in some other parts of the United States, a very peculiar disease appeared, characterized by a rash upon the skin and moderate fever, and a constitutional disturbance proportionate to the extent and severity of the eruption. The malady first broke out in the members of a crew of a private yacht; then in the crews of other boats, and among persons living in the boarding-houses along the docks. It was the cause of a great deal of suffering and disability.

There were three courses open: to accept the disease as a visitation of God, a chastening affliction sent from above, and to call to aid the spiritual arm of the church. Except the "Peculiar People" few now take this view or adopt this practice.

The Christian Scientist would probably deny the existence of the rash and of the fever, refuse to recognize the itching and get himself into harmony with the Infinite. Thirdly, the method of experimental medicine.

First, the conditions were studied under which the individual cases occurred. The only common factor seemed to be certain straw mattresses manufactured by four different firms, all of which obtained the straw from the same source.

The second point was to determine the relation of the straw to the rash. One of the investigators exposed a bare arm and shoulder for an hour between two mattresses. Three people voluntarily slept on the mattresses for one night. Siftings from the straw were applied to the arm, under all of which circumstances the rash quickly developed, showing conclusively the relation of the straw to the disease.

Thirdly, siftings from the straw and mattresses which had been thoroughly disinfected failed to produce the rash.

And fourthly, careful inspection of the siftings of the straw disclosed living parasites, small mites, which when applied to the skin quickly produced the characteristic eruption.

SANITATION

WHEN the thoughtful historian gets far enough away from the nineteenth century to see it as a whole, no single feature will stand out with greater distinctness than the fulfilment of the prophecy of Descartes that we could be freed from an infinity of maladies both of body and mind if we had sufficient knowledge of their causes and of all the remedies with which nature has provided us. Sanitation takes its place among the great modern revolutions-- political, social and intellectual. Great Britain deserves the credit for the first practical recognition of the maxim salus populi suprema lex. In the middle and latter part of the century a remarkable group of men, Southwood Smith, Chadwick, Budd, Murchison, Simon, Acland, Buchanan, J.W. Russell and Benjamin Ward Richardson, put practical sanitation on a scientific basis. Even before the full demonstration of the germ theory, they had grasped the conception that the battle had to be fought against a living contagion which found in poverty, filth and wretched homes the conditions for its existence. One terrible disease was practically wiped out in twenty-five years of hard work. It is difficult to realize that within the memory of men now living, typhus fever was one of the great scourges of our large cities, and broke out in terrible epidemics--the most fatal of all to the medical profession. In the severe epidemic in Ireland in the forties of the last century, one fifth of all the doctors in the island died of typhus. A better idea of the new crusade, made possible by new knowledge, is to be had from a consideration of certain diseases against which the fight is in active progress.