Kairos, Krisis, Rhythmos: Time and Time Awareness in Ancient Medicine Introduction and Background to the Project Time is of the essence in medicine, and Greek and Roman doctors were acutely aware of this. The famous first Hippocratic Aphorism, which sums up what medicine is all about, contains three references to time: the brevity of human life in comparison to the length of time and experience it takes to master the art of medicine; the fleeting nature of ‘opportunity’ (kairos), the right time for medical intervention; and the difficulty of the doctor’s ‘judgement’ (krisis), often to be made under great time pressure in the face of the rapidly changing condition of the patient. Many other ancient medical texts confirm the impression that time, timing and time management were a constant concern for Greek and Roman physicians: symptoms had to be observed at the right time, or at the right moment between time intervals (the so-called ‘critical days’), or over the right period of time, in order to cast a correct and accurate prognosis; treatment had to be applied at the right, critical moment, or for the correct length of time. But what counted as right or correct, and how it should be determined, was subject to difference of opinion among the experts. Diseases were divided into acute (‘fast’, oxys, celer) and chronic (‘slow’, chronios, tardus) diseases, the former requiring rapid action resulting in immediate success or failure, the latter calling for patient, long term monitoring and care with uncertain outcome. But, again, there was debate among ancient medical writers about the classification of some diseases, and about the criteria for distinguishing acute from chronic disease. The human body and its functioning was believed to be subject to specific time cycles, intervals and rhythms, such as the pulse; and irregularities in these rhythms were believed to provide significant clues for diagnosis and prognosis, though opinions differed as to the precise interpretation of these variations and the underlying physiological mechanisms. Many pathological phenomena were believed to manifest themselves in fixed time sequences, such as the periodic fevers mentioned in the case histories of the Hippocratic Epidemics, or symptoms occurring at particular ‘critical’ days in the course of a disease; yet here, too, irregularities and ambiguities gave rise to debate and controversy about the determination and classification of phenomena. The relevant ancient medical texts show a rich and fascinating discourse on time, timing and time management in Graeco-Roman medicine, which was characterised by diversity, debate and competition between rival medical thinkers and schools. They also provide evidence of development and change in medical theory and practice over time, e.g. in pulse theory, diagnostic methods or disease classification. This historical development, too, was something Greek and Roman doctors were aware of, even if Galen in his commentaries on Hippocrates’ Prognosticon and Epidemics tried to bridge the five hundred years gap that separated him from the Father of Medicine by retrojecting many of his own ideas into the Hippocratic source texts.