Henri Roger said: "Laennec in placing his ear on the chest of his patient heard for the first time in the history of human disease the cry of suffering organs. First of all, he learned to know the variations in their cries and the expressive modulations of the air-carrying tubes and the orifices of the heart that indicate the points where all is not well. He was the first to understand and to make others realize the significance of this pathological language, which, until then, had been misunderstood or, rather, scarcely listened to. Henceforth, the practitioner of medicine, endowed with one sense more than before and with his power of investigation materially increased, could read for himself the alterations hidden in the depths of the organism. His ear opened to the mind a new world in medical science." The freely expressed opinions of distinguished German, English and American physicians show that these enthusiastic praises from his French compatriots are well deserved by Laennec for the beautifully simple, yet wonderfully fecund method that he placed before the medical profession in all its completeness. The first employment of the stethoscope by rolling up sheets of paper is of itself a sign of his readiness of invention. He made his own stethoscopes by hand and liked to spend his leisure time fashioning them carefully and even ornately. One of the stethoscopes certainly used by him and probably made by himself is to be seen at the Museum of the College of Physicians of Philadelphia. After three years of study and patient investigation of the use of auscultation in pulmonary and cardiac diagnosis, Laennec wrote his book on the subject. This is an immortal work--a true classic in its complete treatment of the subject. {150} We have had thousands of books written on the subject since Laennec's time, and yet no physician could do better at the present moment than study Laennec's two comparatively small volumes to learn the art of physical diagnosis. It is a characteristic of genius to give a completeness to work that endows it with an enduring independent vitality. Almost innumerable disciples follow in the footsteps of a teacher, and each thinks that he adds something to the fulness of the revelation made by the master. At the end of a century the fourth generation finds that scarcely anything has been added and that the master's work alone stands out, not merely as the great central fact of the new theory or doctrine, but as the absolute vital entity to which the other supposed discoveries are only adventitious and not entirely indispensable accessories.