On August 13, 1826, there died at Quimper in Brittany at the early age of forty-five, one of the greatest physicians of all time. His name, René Theodore Laennec, was destined to be forever associated with one of the most fruitful advances in medicine that has ever been made, and one which practically introduced the modern era of scientific diagnosis. At the present time the most interesting phase of medical development is concerned with the early recognition and the prevention of tuberculosis. To Laennec more than to any other is due all the data which enable the physician of the twentieth century to make the diagnosis of tuberculosis with assurance, and to treat it with more confidence than before, and so prevent its spread as far as that is possible. The history of pulmonary consumption in its most modern phase is centred around the names of three men, Laennec, Villemin, and Koch. To Laennec will forever belong the honor of having fixed definitely the clinical picture of the disease, and of having separated it by means of auscultation and his pathological studies from all similar affections of the lungs. Villemin showed that it was an infectious disease, absolutely specific in character, and capable of transmission by inoculation from man to the animal. To Koch the world owes the knowledge of the exact cause of the disease and consequently of the practical method for preventing its spread. The isolation of the bacillus of tuberculosis is the great triumph of the end of the nineteenth century, as the separation of the disease from all others by Laennec was the triumph of the beginning of that century. There is {136} still room for a fourth name in the list, that of the man who will discover a specific remedy for the disease. It is to be hoped that his coming will not be long delayed. The estimation in which Laennec was held by the most distinguished among his contemporaries, may be very well appreciated from the opinions expressed with regard to him and his work by the best-known Irish and English clinical observers of the period. Dr. William Stokes, who was himself, as we shall see, one of the most important contributors to our clinical knowledge of diseases of the heart and lungs in the nineteenth century, said with regard to the great French clinician whom he considered his master: "Time has shown that the introduction of auscultation and its subsidiary physical signs has been one of the greatest boons ever conferred by the genius of man on the world.