"De l'auscultation médiate" is a medical text written by René Laennec in 1819. It introduced the technique of mediate auscultation, which involves using a stethoscope to listen to internal sounds of the body, particularly the heart and lungs. This method improved the accuracy of diagnoses compared to direct auscultation, where the physician would listen directly to the body. Laennec's work laid the foundation for modern auscultation practices. The stethoscope, which he invented, allowed for a more detailed examination of patients, enhancing the understanding of various diseases. This innovation marked a significant advancement in the field of medicine.