Aristotle’s medical background

1According to the ancient biographies, Aristotle was the son of a doctor, Nicomachus, who was court physician of the Macedonian ruler Amyntas III, and some sources report that his mother Phaestis came from a medical family as well.1 The significance of this distinguished medical family background is enhanced by the fact that in the archaic and early classical period, the family context was traditionally an important setting in which medical teaching and practice was passed on from one generation to another.2 That some ancient sources comment on the fact that Aristotle did not follow his father’s footsteps in the medical profession is itself an indication that it was the normal expectation that he would.3 There is therefore good reason to assume that the young Aristotle will have been exposed to a fair number of medical ideas and practices, and he may well have learned some diagnostic techniques and surgical skills.4

2Furthermore, the geographical names mentioned in the medical writings attributed to Hippocrates point to a considerable spread of medical activity in the North of Greece from the late 5^th century onwards. As several passages in the Epidemics testify, there was a strong presence of doctors on the island of Thasos, which is just opposite Stageira, the place on the main land where Aristotle was born.5 This gives us some idea of the wider intellectual climate in which Nicomachus practised and of the medical theories and approaches with which the young Aristotle may have become familiar.

Aristotle’s views and writings on health, disease and medicine

3Even if Aristotle chose to become a philosopher and a universal natural scientist rather than a medical practitioner, he retained a vivid interest in medicine, as testified by the hundreds of references to health, disease, doctors, medical theory and practice scattered throughout his works.6 In his zoological writings, the De Anima and the Parva Naturalia, he devoted comprehensive and detailed attention to the anatomical structure, the functioning and also the dysfunctioning of human and animal bodies and their parts (especially the heart, the brain, the blood and the genital organs), and to physiological processes such as nutrition, digestion and breathing; and he wrote extensively on reproduction and embryology, growth and development, and on the stages of life and the causes of death. In addition to the extant works, he wrote an illustrated handbook called Anatomai, ‘Dissections’, which contained pictures and diagrams of anatomical structures gained from his extensive practice of (animal) dissection.7 He discussed health, disease and disability in humans and animals (and perhaps also plants)8 in a number of places in his extant writings and in a dedicated (but not extant) work On Health and Disease (or: On the Origins of Disease).9 Furthermore, in a number of more specialized works (or parts of works), he went into greater detail discussing specific medical themes,10 such as heartbeat, pulse and palpitation, nutriment and growth, dietetics, infertility, superfetation and the rearing of children, as well as a range of particular medical questions about various kinds of disease and therapeutic measures.11 In addition, he wrote about the historical development of medicine and collected the opinions of earlier thinkers about the causes of health and disease.12 Unfortunately, most of these works are lost; we know of their existence through references either in Aristotle himself or in other authors, or from titles mentioned in the ancient catalogues of Aristotle’s writings.

4Moreover, in his works on ethics, politics and rhetoric, Aristotle assigned to health a major role in the fulfilment of human life and presented it as a condition for happiness.13 He refers to it as an ‘excellence of the body’,14 which is not just a natural given (like noble birth) or an external good (like wealth) but something to aspire to, something which, at least to a considerable extent, falls within the domain of human control and responsibility and for the acquisition, preservation and restoration of which one should make concerted efforts, if necessary with the aid of a professional expert.15 He further discussed mental health and disorder, especially in the context of various kinds of lack of self control (akrasia, EN VII), and the psychology, physiology and pathology of emotions and desire, i.a. in the context of his famous doctrine of katharsis.16 In addition, Aristotle attached considerable importance to factors promoting health (such as the most beneficial location and orientation of cities), to the role of doctors in social life and to medical expertise in the organisation of the polis, the procreation of children and the upbringing of young citizens.17 At the same time, he posited limitations to the extent to which various human groups were believed to be capable of contributing, physically as well as morally and intellectually, to the successful life of the polis.18

5Furthermore, Aristotle took a profound interest in the medical art as a human activity, as a discipline or field of expertise, and he was intrigued by the epistemological issues it raised, such as the relationship between universals and particulars, or between theoretical and practical knowledge. He frequently mentioned medicine, or gave examples derived from medicine, when discussing such issues.19 And he is reported to have written a dedicated work ‘On the Medical Art’, Peri iatrikês technês, in which he may have gone into these epistemological and methodological questions in more detail. (Again, this work, which is listed in the ancient catalogues, has unfortunately not been preserved).20

6Thus it is clear both from the surviving works and from the fragments and testimonies pertaining to his lost works (or parts of works) that Aristotle held a number of ideas on themes in the sphere of health, disease and medicine. A detailed account of these ideas and their sources, and an assessment of their originality, their place in Aristotle’s thought and their role in the history of medicine would require much more space than is available here;21 suffice it to say that many of these ideas were innovative in their time and influential for many centuries after, and they had great impact on subsequent medical theory and practice, in medical writers such as Diocles, Praxagoras, Erasistratus, Herophilus, Athenaeus and Galen, but also in the school tradition of the Peripatos itself, as represented by Theophrastus, Strato, Clearchus, and later on by Alexander of Aphrodisias.

7Broadly speaking, Aristotle’s investigations in this field were those of a philosopher, or biological scientist, rather than a practitioner or doctor: they were theoretical rather than practical, and primarily driven by a desire for knowledge and understanding (epistêmê) rather than by considerations of skilful application (technê). Yet that does not mean that they were superficial or non-committal, nor that they were devoid of any practical, clinical relevance. As we will see further below, Aristotle was convinced of the pertinence, indeed the vital importance of natural philosophy to medicine, and that of his own natural philosophy in particular; and this made him acutely aware of the need to provide medicine with a solid scientific foundation and to connect natural philosophy and medicine in a better way than had been hitherto attempted. Furthermore, even if Aristotle was not a doctor with hands on practical experience, that did not prevent him from expressing his opinion on medical themes or from stating his preference for certain types of medicine over others. We may draw a parallel here with his extant discussions of rhetoric and poetics: even if he did not lay claim to being an experienced orator or tragedian, Aristotle did not shy away from making a number of strong claims and remarkably detailed personal observations about the best kind of tragedy or the most effective forms of persuasion. It is therefore not at all difficult to imagine that he did something similar for medicine, a discipline with which he was closely familiar, both in other contexts (e.g. in the Parva Naturalia) and in a dedicated discussion of the technê iatrikê.22

Aristotle’s attitude to the medical ideas and practices of his time

8Now in Aristotle’s time, the medical technê was well established in the Greek world.23 ‘Doctors’ (iatroi) were a regular phenomenon in Greek city states and travelling between them, and there was a lively traffic of medical texts, as testified, i.a., by the large number of surviving writings attributed to Hippocrates (the so-called ‘Hippocratic Corpus’), but also by the more than forty 5^th and 4^th century writers on health and disease known to us by name but whose works survive only in fragments.24 Furthermore, medical themes such as health, disease and old age, respiration, fever, embryology, infertility and irregularities in reproduction were discussed by natural philosophers such as Empedocles, Democritus, Diogenes, Alcmaeon, Philolaus, Hippo and Anaxagoras who, like Aristotle, had a more theoretical, scientific interest in health and disease. And, of course, there was Plato’s Timaeus, which devoted an extensive discussion to human health and disease.25 In addition, there were drugsellers, midwives and other practitioners; there was temple medicine, and there were other religious and magical beliefs and practices related to health and disease.

9Even if one leaves religious and magical medicine aside, there was great plurality and diversity of doctrine on matters of health and disease between the thinkers and practitioners of Aristotle’s time: as we can see from the surviving literature of the time, they worked on the basis of sometimes radically different premises and often polemicised against each other.

10Aristotle was well aware of a considerable number of these medical (and philosophical) thinkers and writings on health, disease and medicine, even if the precise extent of his knowledge of the medical literature of his time is difficult to determine. (This is because, with a few exceptions, he hardly ever mentions names or titles of works but usually just refers to ‘doctors’, iatroi).26 He was certainly also aware of the plurality and diversity between medical writers just outlined; for, in his extant writings, he expresses a clear preference for some types of doctor over others. In what appears to be a mixture of descriptive and prescriptive statements in a variety of contexts, he commends doctors who derive the principles of their medical work from the study of nature;27 doctors who have universal knowledge and understanding of the reasons and causes underlying their therapeutic practice of individual patients (as opposed to doctors who rely on experience only);28 and doctors who relate the study and treatment of specific parts of the body, e.g., the eye, to the body as a whole (EN 1102a19–20). He further acknowledges that some doctors also have something to contribute to the study of nature (Resp. 480b27–28).

11Aristotle sometimes refers to these doctors as ‘the distinguished among doctors’ (τῶν δ’ ἰατρῶν οἱ χαρίεντες),29 or as ‘the master craftsmen’ in medicine (οἱ ἀρχιτέκτονες).30 The features that he attributes to these doctors can be found in some of the extant 5^th and early 4^th century medical works handed down under the name of Hippocrates, notably the more ‘philosophical’ works such as Regimen, Sacred Disease, Nature of a Human Being, Breaths, Fleshes and Airs, Waters, Places, and in the fragments of doctors such as Diocles of Carystus; and it is tempting to think that it is these authors, or at any rate authors like these, whom Aristotle has primarily in mind when making these complimentary remarks. They stand out for their broad, liberal-minded, comprehensive approach to medicine, which encompasses not only disease and disability, but also health and things happening according to nature,31 things happening in animals and plants as well as in humans,32 and the health and disease of the soul as well as that of the body.33 A further reason why Aristotle must have thought highly of some of these doctors is that they show an awareness of epistemological and methodological questions regarding empirical observation, inference from signs, causal explanation, and in general sound reasoning. One can imagine that he was impressed by some of their work, both in its own right and because he valued it for its contribution to the study of nature. Indeed, in the passages in the Parva Naturalia quoted above (n. 9), he acknowledges that the work of such doctors constitutes a common ground or overlap with natural philosophy, especially that part of natural philosophy that is concerned with living nature (περὶ τῆς ζωϊκῆς φύσεως, as he puts it in PA 645a6). This overlap or common ground may be regarded as a precursor of what we refer to today as ‘biomedical science’, or ‘the life sciences’. It is therefore not surprising that in his own inquiry into (living) nature, Aristotle takes account of the work of these medical writers where relevant; he evaluates it and recognizes its significance, although he is sometimes severely critical of their views.34

Aristotle’s belief in the importance of (his own) natural philosophy and philosophy of science for medical theory and practice

12Now, it is not that Aristotle believes that this theoretical, philosophical sophistication of doctors is just some kind of intellectual cachet or luxury: he also claims that these doctors are better doctors in actual practice, that their knowledge of the universal (τὸ καθόλου) actually enables them to provide more successful diagnosis and treatment in individual cases (τὸ καθ’ ἕκαστον), as long as they possess sufficient relevant experience (empeiria).35 In a way, Aristotle here anticipates Galen’s claim that in order to be a good doctor, one needs to be a philosopher as well; for to Galen, too, universal knowledge of physics and logic is not just of theoretical significance, it has a direct bearing on medical practice; and its correct or incorrect application in the diagnosis and treatment of individual patients can be a matter of life or death.36

13Furthermore, it is all very well to say, as Aristotle does, that good, scientific medicine should be based on principles derived from physics, the theory of nature. Yet which theory of nature?, we may ask. For there were many of such theories around in Aristotle’s time, and they differed profoundly – just like the medical theories referred to above. Obviously, if the idea of good medicine being based on the principles of the study of nature is to be taken seriously, such medicine must be based not just on any theory of nature, but only on a theory that is true, or at least as close to the truth as possible. This point becomes all the more pressing in the light of Aristotle’s observation that ‘most’ (πλεῖστοι) of those who deal with nature conclude their investigations with a discussion of medicine (Sens. 436a20). That sounds like a good thing, but it can also be deeply disconcerting: just imagine doctors treating patients on the basis of the natural philosophies of Empedocles, Democritus, Anaxagoras or Plato’s Timaeus, with all their errors and fanciful absurdities. You wouldn’t want to go to any of those!

14It is abundantly clear from Aristotle’s criticisms of the views of earlier naturalists (as expressed on several occasions in the Physics and in the biological writings) that he considered his own theory of nature by far superior to those of his predecessors. His observation that good doctors adopt the starting points of their medical theory and practice from the study of nature can therefore hardly be taken as a recommendation that doctors go and borrow their principles from just any of these earlier naturalists. Aristotle must have realized that the superiority of his own natural philosophy had implications for medicine as well. He must have regarded his own natural philosophy as being of vital importance and relevance to medicine, especially those parts that were concerned with the living world and with the health and disease of living beings.

Aristotle’s views on his own place in the history of thinking about health and disease

15There is also a historical dimension to this. For, as we can learn from the doxography on the causes of disease excerpted by the Anonymus Londiniensis (already mentioned above),37 Aristotle also considered and wrote about the historical development of the medical art. And he seems to have done so not just out of antiquarian interest, but because he felt that, in this development, a key moment had arrived: namely, the moment at which medicine, for the first time in its history, could build on a correct understanding of the principles of health and disease and on a truly solid, reliable foundation of natural philosophy and epistemology. We can perceive here a pattern very similar to Aristotle’s doxographical discussions (in his extant writings) of the views of predecessors in physics, psychology and metaphysics, where he presents his own theory as the culmination or completion of a long process of increasing insight, trial and error and growing understanding (this is usually referred to as the ‘dialectical’ use of doxography).

16I argue that Aristotle did something similar with regard to the study of health and disease:38 his project of writing a doxographical account of the views of earlier writers on the causes of health and disease was not just an intellectual exercise devoid of any further scientific or practical significance (as it is usually held to be). Rather, it was designed to pave the way for the presentation of his own theory of the causes of health and disease as the fulfilment of a historical intellectual development. Reading the second part of Anonymus Londiniensis in this way makes good sense: for at first sight, the observation at the beginning of the doxography (Anon. Lond. IV 25–28) of a disagreement (stasis) between two groups of thinkers seems artificial and schematic, and the list of authorities mentioned on either side seems quite selective. They are divided into those who attributed the occurrence of disease to the formation, within the body, of ‘residues arising from nutriment’ (παρὰ τὰ περισσώματα τὰ γινόμενα ἀπὸ τῆς τροφῆς) versus those who attributed the occurrence of disease to ‘the elements’ (παρὰ τὰ στοιχεῖα).39 This does not at all look like an attempt to do historiographical justice to a large variety of ideas; but it is a good example of Aristotelian division (dihairesis). And if we read this presentation of earlier views as a pedagogical pathway leading up to the resolution of this stasis as it was brought about by Aristotle himself, it makes perfect sense. For Aristotle’s own theory of disease actually combined the two factors (residues; imbalance of the elements) that earlier thinkers had separated.40 This latter point is not explicitly made in Anonymus Londiniensis, but we can supplement it from passages in Aristotle’s extant works where he states his own opinion on the causes of health and disease; and it is likely that in the original doxographical survey as Aristotle himself composed it, this was the point where the two separate explanations converged.41

17In presenting things in this way, Aristotle strategically positioned himself into a central place in the historical development of thinking about health and disease: with all due respect to the contributions of predecessors such as Hippocrates and Plato (both prominently mentioned and discussed at considerable length), he showed that a correct, scientific understanding of the nature and causes of health and disease, which is vital for medical theory and practice, had become available only with the advent of his own theory of health and disease, his views on the anatomy and physiology of human and animal bodies, his method of systematic and comparative empirical research (including dissection) and his comprehensive epistemological framework.

18As Aristotle repeatedly says (in the passages listed above in n. 9), health and disease are the business not only of the doctor, but also of the natural philosopher, at least up to the point of discussing their causes or principles. The latter is exactly what the doxography in Anonymus Londiniensis is about.42 And there is something emphatic, almost justificatory about these claims in the Parva Naturalia.43 We can now see why: Aristotle felt that, as a philosopher and biological scientist with medical interests, he had something to offer to medicine that iatroi themselves had so far been unable to provide, not even the ‘distinguished among doctors’ mentioned in the Parva Naturalia and the Nicomachean Ethics; and in these respects, he believed, he distinguished himself from precursors who had made similar claims (and who may have met with controversy, as indicated by the debates in Ancient Medicine and The Nature of a Human Being).

Aristotle’s views on his own contribution to the study of health, disease and medicine

19Let me mention four areas in which Aristotle considered himself to be making important innovative contributions relevant to the study of health, disease and medicine. First of all, there was his comprehensive and comparative survey of the anatomical structures and the functioning of living beings, based on extensive empirical (and to some extent experimental) research into the animal kingdom, including the extensive, systematic use of (animal) dissection, an area in which he claimed to be an innovator – and with good reason, for this practice led to a number of new ideas in anatomy, physiology and embryology.44 Secondly, there was his belief that these empirical investigations had to be guided by a specific theoretical and epistemological framework, in which his conceptual tools of the four causes and the fundamental distinction between necessity and teleology played a central part – distinctions which he believed earlier thinkers, medical as well as philosophical, had failed to make, leading them to errors in observation of the phenomena or in the interpretation of these observations.45 Thirdly, Aristotle claimed to have a better understanding of the nature, the ontological status and the causes of health and disease.46 Health, in Aristotle’s view, is not just a state of balance but a dynamic activity (a praxis) facilitated by such a balance;47 his concept of health is function-related, as it refers to the successful exercise of natural capacities;48 furthermore, health is gradual and relational,49 as it is connected with the generic, specific and individual features of the functioning organism in question.50 And disease, in Aristotle’s understanding, is not something that is contrary to nature without qualification, but a side-effect of natural, goal-directed processes (and thus it poses no threat to his axiom that ‘nature produces nothing in vain’).51 And fourthly, Aristotle claimed to have a better understanding of the mind-body relationship and the mechanics of psychophysical interaction,52 thus enabling more accurate diagnosis and more effective treatment of various kinds of problems in the mental domain (e.g. akrasia), both through somatic measures (dietetics, drugs, surgery) and through certain types of philosophical therapy.53

20The implication of all this is that Aristotle must have regarded himself as a key figure not only in the historical development of (natural) philosophy, but also that of medicine – not by being a doctor (or by playing doctor), but by being a philosopher with medical interests, by providing what he regarded as a true and solid foundation, both theoretical and empirical, for medical theory and practice. With the establishment of his physics/biology and his philosophy of science, Aristotle believed, such a foundation had finally become available: the conditions for truly scientific, and at the same time practically successful medicine were better than ever before!

Aristotle’s attempts to bridge the gap between theory and practice and the clinical relevance of his biological ideas

21Furthermore, Aristotle’s engagement with health, disease and medicine, and his project of medical doxography, was not just a matter of theoretical or intellectual curiosity. There was also a certain practical urgency about it. He recognised the importance of good health for the individual and for the city, and of good medical care in the polis: the doctors he mentions must be properly trained, and work on the basis of the sound principles of (Aristotelian) physics.54

22In this respect, a further biographical detail may not be without relevance: according to one tradition, Aristotle suffered from an internal (stomach or intestinal) disease and died, presumably as a result of this, at the age of 62.55 If this was a chronic condition, it must have brought home to him the importance of good health, and good medical care, even for the philosopher. As he says towards the end of the Nicomachean Ethics, even someone who leads a life devoted to contemplation requires external well-being in order to be happy since, after all, he is only a human being.56 So, ultimately, the purpose of Aristotle’s biomedical project is twofold: for all members of the human species, it is meant to lay the scientific foundation for the provision, preservation and where necessary restoration of health and good quality of life, so that they can fulfil the potential that is available to them; in addition, for the particular case of the philosopher or universal scientist, it is meant to provide him with the ideal conditions, external as well as internal, and somatic as well as psychological, for study and contemplation. No life of contemplation without good health and favourable external conditions;57 no contemplation without sensation or imagination; no sensation or imagination without healthy and good functioning sense organs; and no healthy mind without a healthy body.

23Aristotle’s realization of the importance of good health for the individual and for the community, and of his own philosophy as the best and most suitable foundation for the understanding and provision of health, raises the question of how this translates into actual practice. This is anything but obvious, for there can be quite a gap between theoretical, knowledge-driven biomedical research and the application or implementation of such knowledge in medical practice.58 Bridging that gap was all the more important considering Aristotle’s claim (which we already mentioned above) that doctors with universal, theoretical knowledge are also better doctors in actual practice. In order to substantiate this claim, Aristotle had to address the question about the translatability of theoretical knowledge into practical action. This involved, inter alia, the question of the extent to which doctors should have knowledge and understanding of the fundamental principles of the natural world: for while it is clear from the passages in the PN quoted above that there is some common ground between natural philosophers and doctors, one may ask whether doctors can be expected to go all the way to the most basic aspects of reality, let alone to provide a demonstration of this59 – just as, conversely, one may wonder whether and, if so, how far natural philosophers’ discussions of health and disease will go beyond a general statement of the principles of health and disease and extend their project to the discussion of specific diseases, diagnosis and therapeutics.60

24Regarding these matters, Aristotle has important things to say about the relationship between universals (τὸ καθόλου) and particulars (τὸ καθ’ ἕκαστον) and between theoretical and practical knowledge in practical disciplines such as ethics and medicine, and about the importance of experience (empeiria) enabling the doctor to diagnose individual patients as instances of a more general type or to identify individual substances or procedures as the appropriate remedies instantiating, in a given case, a more general therapeutic principle or mechanism.61 He often uses medicine in analogies with ethics as the prime example of a practical (or productive) science making considered and selective use of universal, theoretical principles and achieving its aims only by approximation, not by absolute precision (akribeia), just as the moral philosopher needs to have some knowledge of the science of the soul yet not to the full extent that is required in physics.62

25Furthermore, in his extant writings on zoology, we can perceive attempts, on Aristotle’s part, to bridge the gap between theory and practice by attaching to his statements a certain clinical, i.e. diagnostic or therapeutic significance. This may take the form of stating the underlying causes of phenomena, thus allowing the observer (e.g. the doctor, or the patient) to distinguish physiological from pathological conditions and to obtain a better understanding of the underlying mechanisms. For example, in Respiration, his account of breathing is structured in such a way as to demonstrate the relevance of a scientific understanding of the anatomy and physiology of respiration and related processes for a correct biomedical interpretation of related empirical observations, such as the pathological phenomenon of palpitation and the natural phenomenon of pulsation.63 A further example is Aristotle’s discussion of the brain in PA II.7 and GA II.6, where one of the consequences of his account is that a medical doctor feeling the softness of the bregma in new born children will, as a result of Aristotle’s explanation, be able to make sense of this tactile experience and assess it correctly as a sign of health rather than illness; he will also be able to interpret correctly the difficulty people may have in raising their eyelids in situations of fatigue or drunkenness.64 A third example, taken from the mental domain, is his distinction (in EN VII) between various conditions manifesting themselves in lack of self control (akrasia), a distinction that has important implications for diagnosis as well as treatment.65 Reading the discussion of akrasia in EN VII from this ‘clinical’ point of view, we can see a patient emerging with a specific type of problem calling for a specific mode of treatment.66 Once one starts looking for it, one can perceive many more examples of a concern, on Aristotle’s part, with what we might call the connectibility (the ‘Anschlussfähigkeit’) between natural philosophy and medicine, with ways in which natural philosophy could be made suitable for application in the medical art or could contribute to better informed medical practice.67

26There is also a flipside to this. As stated, Aristotle recognized that good doctors have something to say about nature (Resp. 480b27–28). This is presumably because he realized that life-long experience in clinical practice, e.g. in the observation of patients’ symptoms (as recorded in the ‘Hippocratic’ Epidemics) or in surgical treatment, may give rise to new insights in anatomy or physiology. Furthermore, he was sympathetic to the idea (as expressed, for example, in The Sacred Disease) that diseases are part of nature and that their understanding thus contributes to the study of a part of nature.68 In accordance with that realization, he frequently considers pathological aspects of a specific phenomenon, process or function as a source of information about the natural state of things.69 He often refers to disturbances in the functioning of certain capacities (e.g. memory, sleeping and dreaming) in order to show or illuminate aspects of these functions that are also present, but less visibly, in the healthy state.70

Aristotle, the Peripatos and medicine in the fourth and early third century BCE: The implementation of a programme

27Looking beyond Aristotle at his immediate successors in the Lyceum, we can perceive a remarkable amount of attention being paid to medical themes. Medicine is the dominant science in the Problemata physica;71 and Theophrastus, Strato and Clearchus write dedicated works on themes such as fatigue, dizziness, sweating,72 fainting, suffocation, paralysis, delirium, excretions, hair, old age, sleep, epilepsy, melancholy, respiration, diseases, crises, epidemic diseases, and mummified bodies.73 Moreover, in his botanical writings, Theophrastus devotes a considerable amount of attention to the health and well being of plants and to the diseases they may suffer from.74 He frequently observes that certain plants thrive (using terms such as εὐθενεῖν, εὐθηνεῖν, εὐσθενεῖν, εὐημερεῖν, ‘well-being’, ‘being in good shape’, ‘flourishing’, ‘thriving’), which manifests itself in vigour and resistance, good appearance and fertility. He discusses the causes of such thriving, and considers both plants’ internal structures and features as well as the places, circumstances and external conditions under which plants’ well-being is possible.75 But he also mentions on numerous occasions diseases (nosêmata) by which plants may be affected, and he explains why and how these come about.76 He even offers dedicated discussions of the phenomenon of disease as such, its causes,77 its various manifestations in the form of specific types of disease,78 and the treatment or prevention of these conditions.79 At the same time, he regularly refers to the medicinal effects of plants and trees, both in the course of his discussion of individual plants and in a dedicated discussion in book 9 of HP (from ch. 8 onwards).

28Now, like Aristotle, Theophrastus writes as a student of nature (phusikos), whose primary purpose is universal knowledge and understanding. He is not a farmer or forester trying to apply this information in agricultural practice, nor a rootcutter, herbalist or doctor seeking the use of medicinal plants and their parts for the treatment of human or animal disease (although he frequently refers to such practitioners). Yet that does not prevent him from going into extensive detail, not only when it comes to the morphology of plants and their functioning but also when considering their dysfunctioning; and he allows for a wide scale of degrees of optimal, sub-optimal or downright poor performance. As I suggested above in connection with Aristotle, one possible reason (beyond sheer curiosity) for this remarkable amount of detailed attention, on Theophrastus’ part, to questions of health and disease is a concern to provide practical disciplines, in this case agriculture and medicine, with scientifically grounded information relevant to application in actual practice. This is not to say that his botanical works were addressed to farmers or rootcutters, for, as said, they are part of a scientific enquiry into the natural world, not practical handbooks as we find them in later classical literature (e.g. Varro, Columella); and even his numerous references to husbandry (γεωργία), tendance (θεραπεία), treatment (βοηθεία) or prevention (φυλακή) are not in the form of practical instructions but statements of information about agricultural practice which add to the understanding of the phenomena that are being described or of the explanation that is being provided. Nevertheless, there is a clear relevance, in such statements and elsewhere, to practical application.80 It is quite plausible that, like Aristotle, Theophrastus may have been motivated by the consideration that, as a philosopher and biological scientist, he had something to offer that farmers, rootcutters and doctors themselves were unable to provide: a true and solid theoretical foundation, both physical and epistemological, for practical engagement with the health and well-being of plants and the cure or prevention of the diseases they may suffer from – or more generally the factors that influence their quality of life and performance.81 Something similar applies to his account of the medicinal powers of plants, which engages with medical writers and rootcutters (and with folk beliefs) but which adds a theoretical dimension, including a brief discussion of questions of causation.82

29At the same time, the Lyceum took developments in medicine on board: Theophrastus and Strato show familiarity not only with a number of ‘Hippocratic’ writings but also with more recent medical writers such as Diocles, Herophilus and Erasistratus.83 And affiliations between the Peripatos and the Alexandrian biomedical scientists are attested in the biographical tradition.84 The Lyceum clearly was a centre of intellectual exchange and debate which attracted scientists and philosophers from other parts of the Mediterranean world, one did not have to be a ‘member’ or a ‘student’ in order to take part in its activities. There is a clear impression that there was lively interaction and dialogue going on between natural philosophers and doctors – a dialogue already envisaged and carried out by Aristotle himself but continued and intensified by the Peripatetics, who went further and in greater technical detail than Aristotle himself had done, but who were working in the spirit of their master.

30I suggest that we regard this as the implementation of a kind of programme or agenda, with the aim of further strengthening the theoretical, scientific foundation for medical practice and thus for the realization of the connection between medicine and natural philosophy that Aristotle himself had outlined.

31A good illustration of what I mean by implementation of a programme can be found in the first book of the extant Problemata physica, that large collection of questions and answers about the natural world brought together in the Peripatetic school. Book I is entirely devoted to medical questions (hosa iatrika). It contains verbal quotations from medical writings such as Airs, Waters, Places and the Aphorisms (further evidence of the extent of detailed familiarity with medical literature in the Lyceum).85 And it goes into a remarkable amount of specific detail, not only about the causes of disease but also about diagnosis (e.g. ch. 51 on uroscopy) and therapeutics. Indeed, some chapters (e.g. 55 and 56, on the treatment of people suffering from various kinds of fever) almost read like the discussions we find in the ‘Hippocratic’ works Diseases I, II, III or Regimen in Acute Diseases. Yet the approach is that of Aristotelian natural philosophy. That is not surprising, for the title of the work is, after all, Problemata physica.86 And the questions asked in Book I are all about efficient and final causation. This corresponds very nicely to what is being said in Metaphysics I.1 about the master craftsman in medicine: stating the causes of health and disease, stating the causes of the (non-)efficacy of treatment, stating the purpose or benefit (the ἕνεκά τινος, the ἀρετή) of a particular remedy. Whether Probl. I goes back to Aristotle himself or to a later Peripatetic is not relevant for our point here: the Problemata provide illuminating examples of subject specific implementation of what Aristotle had prescribed.

32Thus the study of health, disease and medicine from the viewpoint of natural philosophy is vigorously being pursued in the Peripatos; and in this context, doctors’ contributions to the study of nature continue to be acknowledged. One such doctor is Diocles of Carystus. As I have argued elsewhere,87 it seems very likely that Diocles and Aristotle were contemporaries who were aware of each other’s work and in dialogue with each other, and it makes good sense to interpret certain passages in their writings as the result of interaction. Diocles is reported to have written on (comparative) anatomy and to have practised dissection of animal bodies;88 he was known for his interests in the theoretical, methodological and epistemological aspects of the medical art (causal explanation, inference from signs); moreover, two fragments (23c and 23d; 182.11) attribute to him a teleological way of thinking about bodily structures. Aristotle’s work in zoology, his use of dissection, his broad empirical fieldwork and the epistemological framework in which it took place, is very likely to have appealed to Diocles, whose work and intellectual personality display very similar characteristics. If more of Diocles’ works had survived, we would have been in a better position to imagine what impression his work may have made on Aristotle and his followers; but the extant evidence suffices to show that Diocles’ profile neatly suits Aristotle’s picture of the liberal-minded, “distinguished doctors” whom he commends in the PN for taking an interest in natural philosophy and “having something to say about nature”, or Aristotle’s portrayal of the medical “master craftsman” in Metaphysics I.1, who gives account of his diagnostic and therapeutic decisions by stating the causes of the remedies he is recommending. Diocles meets all these requirements and seems to represent the ideal physician who was both a theoretical thinker and an experienced practitioner.

33Moreover, close analysis of the type of causal explanation provided in the Problemata shows an awareness of some of the methodological issues raised about causal explanation by Diocles.89 In the famous methodological fragment 176, Diocles expresses some important reservations about causal explanation in dietetics.90 His position here is so carefully elaborated and nuanced, and the resemblances with some of Aristotle’s remarks in the Metaphysics and the Ethics (and with some of Theophrastus’ remarks, both in his Metaphysics and in the botanical works) are so striking that we can well imagine how it will have resonated with Aristotle and his students, how it may have inspired a dialogue, or how Diocles’ position as stated in the fragment is the result of such a dialogue. There is a methodological discussion going on here at a very high level, affecting not only issues in the philosophy of science but also actual research and clinical practice; we can see this both in Aristotle and in his followers in their study of nature, and in their practice of seeking to find the cause in medicine.

34Further evidence of interaction between the Lyceum and the medical thinkers of the time is provided by Praxagoras of Cos, whose ideas on the anatomy of the blood vessels show remarkable parallels with those of Aristotle,91 and by the two leading medical doctors and biological scientists of the next generation, Herophilus and Erasistratus. They are well known for their revolutionary discoveries about the brain, the nerves, and the heart, based on empirical and experimental research into the structure and functioning of living beings through dissection of animal and human bodies. Yet it has been increasingly appreciated that in their use and method of dissection, in the questions leading their anatomical investigations and in their approach to living nature as a whole, they were inspired by Aristotelian viewpoints and driven by research questions that are strongly reminiscent of Aristotelian science.92 In their efforts to build their medical research and practice on a theoretical foundation, both physical and epistemological, they, too, can be seen to be implementing an Aristotelian programme.

35More in general, I would like to argue that Aristotle’s biomedical project had an important role in the development and establishment of what later came to be called ‘Rationalist’ (logikos) medicine. As I have argued elsewhere, Aristotle’s portrayal of Hippocrates as testified in the Anonymus Londiniensis contributed to the perception of Hippocrates as the founder of Rationalist medicine.93 Much of what Aristotle and the Peripatetics had to say on the theoretical foundations of medicine was taken on board by a Hellenistic medical writer such as Athenaeus of Attalia, and by an early Imperial medical thinker such as Galen, whose work was profoundly influenced by Aristotle, even if Galen was not always prepared to acknowledge this.94

A question of critical self-examination: Is my reading of Aristotle too Galenic?

36This brings me to a final question: is my reading of Aristotle too Galenic? Is it unduly influenced by my work on Galen’s reception of Aristotle, by Galen’s views on the relationship between medicine and philosophy and on his actual practice in elementary physiology?95 Of course, one difference between Galen and Aristotle is that Galen was a practising doctor as well as a philosopher, whereas Aristotle was probably not involved in medical practice. Yet that difference is not decisive for the point that is at issue here. There is no doubt that Galen to a large extent put into practice the ideal of medicine based on the principles of Aristotelian natural philosophy and philosophy of science (though in both respects, Galen had other sources of inspiration as well). Yet I would argue that the above points, about the connection between natural philosophy and medical thought and practice, are applicable to Aristotle as well. I would at any rate claim that the specific interpretation of Aristotle’s engagement with health, disease and medicine given above is preferable to the standard view, which is that Aristotle was simply interested in everything and thus also in medicine. In my view, Aristotle’s biomedical project was not just part of his scientific endeavour (his desire to understand) but also driven by considerations of practical relevance and urgency; it was grounded in the belief that health is a condition for successful ethical and social activity and that the polis should have good medical care in order to make this possible; and it was founded in the confidence that Aristotelian philosophy provided the best basis for this.