Here and there through the various silent battles between human beings and bacteria there stand out heroic figures, men whose powers of mind and gifts of insight and observation have made them the generals in our fight against the armies of disease. But their gifts would have been wasted had they lacked the one essential aid without which leadership is futile. This is the force of enlightened public opinion, the backing of the every-day man. It is the cooeperation of every-day men, acting on the organized knowledge of leaders, which has made possible the virtual extinction of the ancient scourges of smallpox, cholera, and bubonic plague. Just as certain diseases are gradually passing into history through human effort, and the time is already in sight when malaria and yellow fever, the latest objects of attack, will disappear before the campaign of preventive medicine, so there are diseases, some of them ancient, others of more recent recognition, which are gradually being brought into the light of public understanding. Conspicuous among them is a group of three, which, in contrast to the spectacular course of great epidemics, pursue their work of destruction quietly, slowly undermining, in their long-drawn course, the very foundations of human life. Tuberculosis, or consumption, now the best known of the three, may perhaps be called the first of these great plagues, not because it is the oldest or the most wide-spread necessarily, but because it has been the longest known and most widely understood by the world at large. Cancer, still of unknown cause, is the second great modern plague. The third great plague is syphilis, a disease which, in these times of public enlightenment, is still shrouded in obscurity, entrenched behind a barrier of silence, and armed, by our own ignorance and false shame, with a thousand times its actual power to destroy. Against all of these three great plagues medicine has pitted the choicest personalities, the highest attainments, and the uttermost resources of human knowledge. Against all of them it has made headway. It is one of the ironies, the paradoxes, of fate that the disease against which the most tremendous advances have been made, the most brilliant victories won, is the third great plague, syphilis--the disease that still destroys us through our ignorance or our refusal to know the truth.