It is this orientation toward innovation, and this commitment to scientific advancement, that the teaching hospital has contributed to the long history of hospitals. In other areas of its development, such as the emphasis on emergency care, the teaching hospital shares a trend evident among all hospitals everywhere, though it displays the trend in a more pronounced form.

The evolution of the hospital has been going on for more than two thousand years, beginning with the first system of hospitals about which much is known, the aesculapia of Greece. These first appeared around 350 b.c., taking the form of temples to Aesculapius, a deified physician who had lived nearly a thousand years earlier. (Homer insists that Aesculapius was a mortal, despite the fact that he was a pupil of the centaur Chiron.) The legendary fate of Aesculapius is ironic, for it represents the first statement that good medical care could lead to population problems. According to legend, Aesculapius was so successful as a healer that Hades became depopulated; Pluto complained to Zeus, who eliminated Aesculapius with a thunderbolt. The Aesculapian temples were not so much hospitals as religious institutions where patients came on pilgrimages, hoping to be cured by a visitation of the gods; the medical historian Henry Sigerist suggests Lourdes as the closest modern parallel.

Predictably, the most common cures were of people suffering from what would now be called hysterical or psychosomatic illness-headache, insomnia, indigestion, blindness caused by emotional trauma, and so on.

The hospital in a more modern sense began in late Roman times, and coincided with the spread of Christianity across Europe. The word "hospital" is derived from the Latin hospes, meaning host or guest; the same root has given us "hotel" and "hostel." Indeed, the first hospitals were little different from hotels and hostels. Essentially they were places where the sick could rest and be fed until they recuperated or died. All hospitals were run by the Church, and most were associated with monasteries. Medicine was practiced by monks and priests.