Monaural stethoscopes from the collection of The Mütter Museum of The College of Physicians of Philadelphia.

Physical examinations by physicians for millennia were limited to the exploration of the outside of the body or to the substances produced by the body. Doctors palpated, measured the pulse, looked into eyes and mouths, and examined urine, stool, sputum, blood and vomit. Doctors combined the results of their observations with the description of symptoms provided by a patient in order to determine illness and treatment.

The merger of observation and patient description of symptoms was enhanced by technological developments that began to occur in Paris during the French Revolution with the abolition of the existing medical faculties in 1789. This erasure of medical tradition created the precursor to modern medical education: surgery was combined with medicine, students were taught in clinical settings, and the dissection of cadavers became part and parcel of a student's medical training.

One of the students of the new medical schools in Paris was René-Théophile-Hyacinthe Laennec, who was born in 1781. Laennec became a doctor in 1804, and in 1816 made an observation that changed what occurs during a visit to a doctor's office forever. Laennec examined a rather stout young woman whose symptoms indicated heart disease. The patient was too fat for percussion to be useful, and social constraints dictated that the good doctor not place his ear directly to the patient's chest. So Laennec rolled up a notebook, and placed it upon his patient's chest, and realized that his device amplified and clarified the sound of his patient's beating heart. The "stethoscope," from the Greek words for "chest" and "explore," was born.

The willingness of doctors to use mediators such as the stethoscope encouraged the use of a technology that was first developed by Hans and Zacharias Jansen in 1590: the microscope. Distrust of anything that could not be seen by the naked eye gave way to improvements in microscopic technologies, and by the mid-19th century, medical students were introduced to microanatomy, and the concepts of tissue and cells.