Humboldt-Universität zu Berlin - Faculty of Language, Literature and Humanities - Alexander von Humboldt Professorship

Kairos, Krisis, Rhythmos: Time and Time Awareness in Ancient Medicine

Within the Einstein Center CHRONOI ( and with the financial support of the Einstein Foundation (, the Alexander von Humboldt Professorship in the academic year 2019-20 conducted a research project on the following theme:


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.     

Against this background, this research group  has examined two specific, interrelated themes that provide vivid and detailed illustrations of concepts of time and time awareness in ancient medicine, and of the debates surrounding these:


Pulse Rhythm and Pulse Measurement

The first theme was Graeco-Roman medical ideas (and related practices) about the pulse, its measurement, its diagnostic significance and therapeutic management, its underlying anatomical structures and physiological mechanisms and its relationship to other rhythmical movements in the body, such as respiration, tremor and various kinds of heart-beat. While pulsation (sphygmos) was referred to by Hippocratic medical writers and by Aristotle, it was not before the early Hellenistic Age that major importance was attached to the pulse both as a physiological mechanism and as a diagnostic or prognostic indicator of disease; and elaborate theories and classifications of pulse rhythms were developed, especially by the Alexandrian doctor Herophilus and his followers. Methods were developed to identify and distinguish these pulse rhythms in a wide range of bodily conditions, fevers and other diseases; and a terminology was designed to describe these rhythms and to communicate them to others, e.g. medical students learning to take the pulse. This terminology made use of metaphors derived from metre and musical theory, or from the domain of animal movement (e.g. the ‘ant-like’ pulse, the ‘gazelle-like’ pulse). Herophilus’ work on the pulse was further developed by the so-called Pneumatist medical writers, by the first/second century CE medical writer Marcellinus and of course by Galen, who wrote four extensive and influential treatises on the different kinds of pulse, the identification of these different kinds, the causes of pulses and the prediction on the basis of pulses.     


Critical Days and Periodic Fevers

The second theme was Graeco-Roman medical concepts of crisis, critical days and periodic fevers. These concepts can already be found in the Hippocratic writings, where krisis not only stands for the doctor’s judgement (as quoted in the Aphorism above) but also for the critical, decisive moment in the course of the disease itself, leading either to recovery or to death. The doctor’s correct determination of this turning point and, where possible, the ensuing medical intervention were believed to be crucial for the patient’s chances of survival. Likewise important, especially for prognosis, were the specific ‘critical days’ at which certain symptoms manifested themselves, and ancient doctors developed elaborate numerical series and calendars indicating which days and which time intervals were significant as indicators of specific diseases or as prognostic clues. Within these systematisations, the typical periodic fevers (quotidian, semitertian, tertian, quartan, etc.) attracted special attention and occupied an important place in theories of disease (in ancient medicine, fever was mostly considered a disease in its own right, not a symptom). But the more elaborate these systems became, the greater were the disagreements about their reliability and their practical usefulness. Again, changes took place in the conceptualisation and classification of these phenomena over time; and in the Imperial period, the system of critical days was also connected with astrological calculations. Galen’s treatises On Crises, On Critical Days and On the Different Kinds of Fever provide vivid, detailed evidence not only of his own understanding of these themes but also of the debates and disagreements surrounding them.       


Constitution of the Research Group

The project was carried out by a research group consisting of the following Einstein Fellows:

Glen M. Cooper focused on Galen’s writings On Crises and On Critical Days and their reception in Islamic medicine. He is preparing critical editions of the Greek and the Arabic versions of these works with translation and commentary for the Brill series Studies in Ancient Medicine and for Ashgate.

Sean Coughlin concentrated on the pulse theories of the Pneumatist medical school, in particular Athenaeus of Attalia, an important precursor of Galen. He is preparing a collection of the fragments of Athenaeus for the Brill series Studies in Ancient Medicine.

Orly Lewis concentrated on the pulse theories of the Pneumatist medical school, in particular Archigenes of Apamea, an important precursor and rival of Galen. She is preparing a monograph on Archigenes for the Brill series Studies in Ancient Medicine.

Christine Salazar worked on concepts of crisis and critical days in Galen’s commentaries on works attributed to Hippocrates, especially the Prognosticon, the Aphorisms and the Epidemics. She is preparing a translation with commentary of the Commentary on Hippocrates’ Prognosticon for the Cambridge Galen Translations.

Peter N. Singer focused on Galen’s treatises on the pulse, which are the most substantial surviving account of ancient pulse theory. He is preparing a translation with commentary of these works for the Cambridge Galen Translations.

Philip van der Eijk co-ordinated the research group. He worked on theories of periodic fever in the Aristotelian tradition, focusing in particular on the treatise On Fevers attributed to Alexander of Aphrodisias, which shows close parallels to Galen’s On the Different Kinds of Fever, and on two treatises on fevers and pulses attributed to the Aristotelian commentator John Philoponus. This project arose from his current work on a monograph on Aristotle, Aristotelianism and Ancient Medicine, which he is preparing for publication by Cambridge University Press.


The group had weekly meetings discussing work in progress. In conclusion, it organized a workshop summarizing the results of the project (see