With regard to heart disease, it was before Laennec's discovery almost a sealed chapter in practical medicine. It was known that people died from heart disease often and, not infrequently, without much warning. The possibility that heart conditions could be separated one from another, and that some of them could be proved to be comparatively harmless, some of them liable to cause lingering illness, while others were surely associated with the probability of sudden fatal termination, was scarcely dreamed of. It is to Laennec's introduction of auscultation that modern medicine owes all its exacter knowledge of heart lesions and their {148} significance. He himself did not solve all the mysteries of sound here as he did in the lungs; indeed, he made some mistakes that render him more sympathetic because they bring him down to the level of our humanity. He did make important discoveries with regard to heart disease, and his method of diagnosis during his own life was, in the hands of the Irish school of medicine, to prove the key to the problems of disease he failed to unlock. Almost at once Laennec's method of auscultation attracted widespread attention. From Germany, from Italy, from England, even from the United States, in those days when our medical men had so few opportunities to go abroad, medical students and physicians went to Paris to study the method under the direction of the master himself and to learn from him his admirable technique of auscultation. Those who came found that the main thing to be seen was the patient observation given to every case and Laennec's admirably complete examination of each condition. The services to diagnosis rendered by the method were worthy of the enthusiasm it aroused. Only the work of Pasteur has attracted corresponding attention during the nineteenth century. Physicians practice auscultation so much as a matter of course now that it is hard to understand what an extreme novelty it was in 1820, and how much it added to the confidence of practitioners in their diagnosis of chest diseases. Bouilland said, with an enthusiasm that does not go beyond literal truth, "A sense was lacking in medicine and I would say, if I dared, that Laennec the creator, by a sort of divine delegation of a new sense, supplied the long-felt want. The sense which medicine lacked was hearing. Sight and touch had already been developed in the service of medical diagnosis. Hearing was more important than the other two senses, and in giving it to scientific medicine Laennec disclosed a new {149} world of knowledge destined to complete the rising science of diagnosis."