Greek medicine and the Hippocratic Oath

Long before hospitals, ancient Greeks who fell ill often turned to the gods. The god of medicine was Asklepios, the son of Apollo. Two goddesses were linked with him: his daughter Hygieia, “Health”, and Panakeia, “Cure-all”. In Homer’s Iliad, his two sons, Machaon and Podalirios, are healers who look after wounded warriors at Troy.

Sick people travelled to the sanctuaries of Asklepios, the Asklepieia. The most famous was at Epidaurus, in the Peloponnese, where Asklepios was worshipped from the 6th century BC. Patients washed, made offerings and then slept in a special hall, the ἄβατον. This healing sleep was called ἐγκοίμησις. They hoped that the god would appear in a dream and tell them which treatment to follow.

But Greece also had doctors who were craftsmen, not priests. A doctor was an ἰατρός, and today Greeks still say γιατρός. He visited patients at home, examined them and advised food, rest, exercise or medicines. On this page you will meet the most famous of these doctors, Hippocrates of Kos, and the oath that carries his name.

Hippocrates came from the island of Kos, in the south-east Aegean, and lived in the 5th century BC. We know very little about his life. Plato mentions “Hippocrates of Cos, the Asclepiad” as a famous teacher whom a young man could pay to learn medicine (Protagoras 311b). The Asclepiads were a family of doctors who traced their line back to Asklepios.

About sixty medical books have come down to us under his name: the Hippocratic Corpus. They were probably written by several authors over a long period, and they sometimes give different advice. We cannot be sure which of them, if any, Hippocrates wrote himself.

What links many of these books is a new way of thinking. The author of On the Sacred Disease says that epilepsy, which many people blamed on the gods, has “a natural cause” like other illnesses, and that people call it divine only because they do not understand it. Some Hippocratic writers explained health as a balance of four fluids in the body: blood, phlegm, yellow bile and black bile.

The great sanctuary of Asklepios that visitors see on Kos today was built mostly after Hippocrates, from the 4th century BC onwards. The Greek Ministry of Culture links the scientific medicine practised there to the school that Hippocrates had founded on the island.

The Hippocratic doctors learned by watching their patients closely. In Epidemics I (section 11) the writer gives a short rule: “Declare the past, diagnose the present, foretell the future.” Two Greek words behind this method are still key terms of medicine. Διάγνωσις, from διαγιγνώσκω, “to tell apart”, is the work of deciding which illness a patient has. Πρόγνωσις, “knowing in advance”, is the forecast of how the illness will develop; one Hippocratic book is called the Prognostic.

The same passage adds: “As to diseases, make a habit of two things: to help, or at least to do no harm.” It also says that the art has three parts, the disease, the patient and the doctor, and that the patient must work with the doctor against the disease.

The main tool of treatment, the θεραπεία, was often δίαιτα: not only food, but the whole way of living, with rest, exercise and baths. A φάρμακον could be a healing drug, but the same word could also mean a poison, so a doctor had to be careful with it.

The Ὅρκος, the Oath, is a short text in the Ionic Greek of the Hippocratic books. It begins ὄμνυμι Ἀπόλλωνα ἰητρόν, “I swear by Apollo Physician”, and calls Asklepios, Hygieia, Panakeia and all the gods as witnesses. The new doctor then promises:

• to honour his teacher like a parent, and to teach the art to his teacher’s sons without a fee;
• to use regimen “for the benefit of the sick”, and never to harm them;
• not to give a deadly drug to anyone who asks for it, and not to give a woman a pessary to cause abortion;
• not to cut for stone, but to leave this to the men who do such work;
• to keep silent about what he sees or hears “in treatment”, ἐν θεραπείῃ, and outside it.

Who wrote it, and when? We cannot know whether Hippocrates himself wrote it. It is often dated to the late 5th or the 4th century BC, but this is debated: in 2019 the classicist Cristian Tolsa argued that its ethical rules may be a later, Hellenistic addition to an older oath of loyalty to the teacher. In 1948 the World Medical Association adopted a modern pledge, the Declaration of Geneva, which some medical schools now read at graduation.