One of the finest products of the Greco-Roman imagination is the fifth book of Lucretius' poem De rerum natura. In magnificent language the Latin poet pictures the successive stages of the evolution of the cosmos from clouds of atomic dust, and with great intensity displays the explanatory advantages of his materialism over the cosmic gods of ancient mythology and rival philosophies. First comes the framework of the cosmos: earth and sun, the stars, planets, sun and moon, and the seasons of the earth. Then the poem goes on to tell of the first growth of vegetation, the emergence of animal life, the earliest human communities, the growth of civilization and technology, the development of political structures, and the genealogy of morals.

There can be little doubt that the Atomists of the fifth century b.c. wrote about these things too, and that many of their ideas were adopted by Epicurus and his Greek followers, who were themselves the sources of Lucretius' inspiration. It happens that Lucretius' poem has survived intact, while the work of Leucippus and Democritus has vanished. The fifth book of De rerum natura, then, is our best source for this aspect of ancient Atomism. Nevertheless, it seems appropriate to study Lucretius in his Epicurean context, rather than as an appendix to Democritus. Although there is in all probability much in Lucretius book v that comes from Democritus, there is certainly much that does not. So at the cost of leaving our history of Preplatonic Atomism embarrassingly threadbare in this area, we shall not draw on Lucretius' anthropology for evidence here, and postpone the attempt to give a more satisfactory account of the atomic theory to volume 2.

The beginning of the fifth century b.c. – the time when Greek civilization was menaced by the expanding might of the Persian Empire, and managed to save itself from being overwhelmed – is a period of some confusion for the literary historian. The materials he has to work with consist of the Victory Odes of Pindar, some other specimens of lyric poetry, and a few of Aeschylus' plays. In philosophy, we have a chancy collection of the fragments of Heraclitus, Parmenides, Anaxagoras, and Empedocles. Hardly anything else is preserved in sufficient quantity to allow a critical view to be taken of it, or even to provide background against which we can locate the works that have survived. It is possible that our histories do some injustice, by concentrating on the known names and works, to others whose efforts were at the time of equal importance. But we have no choice: we can only endeavor to make the most of the available evidence. Some have tried to supply the background that is missing from the Greek inheritance by looking at other cultures, especially those of the Near East. It is, of course, right to make the effort, and for the period when the transmission was not by written texts but oral, and when myth dominated the poetic scene, the comparisons have proved invaluable. In my opinion they have been much less successful and illuminating for the period when, with the growth of literacy, philosophy and the exact sciences were emerging from the mythical background.

The infinite universe

It is particularly important, when writing about the Atomists, to be consistent in making the distinction between the universe or ‘the all’ (to pan, in Greek) and the world (kosmos) – that is, a particular part of the universe consisting of our earth, sea, air, and visible stars, planets, moon, and sun. Leucippus and Democritus held that ‘the all’ consists of an unlimited expanse of void space and an unlimited number of atoms. Of these, some are – temporarily – arranged so as to form worlds, including the world in which we live. We must study, first, the arguments used to defend the notion of the unlimitedness of the universe, and then the mechanisms that were suggested to account for the formation of worlds.

If we are to understand the controversy of classical antiquity, we must keep clearly in mind one important difference between ancient and modern cosmology. In the twentieth century we have grown accustomed to the notion that what we see in the sky on a starry night is the beginning of a universe that continues far beyond the limits of our vision. We can see some of the stars, because they are relatively large, bright, and near; with telescopes we can see further into the distance and see more stars, and with better telescopes we could see further still. In the cosmology of classical antiquity, on the other hand, it was a matter of common agreement that the stars we see are part of our world: they are the boundary beyond which the infinite universe (if it is infinite) begins.

There are many good histories of early Greek philosophy, and it is not necessary to the purpose of this book to attempt to rival them. We must try to pick out the themes outlined in the earlier chapters, without encumbering the narrative with too much detail. The reader must be warned, however, that this selectivity is certain to be controversial. The evidence for the theories of the sixth and fifth centuries b.c. is scrappy and ambiguous: we lack the context of the short quotations that survive – the longest consecutive fragment is sixty-six lines of verse. It is just possible that we have the whole intent and direction of some fragments wrong. That is not likely, because the tradition has been subjected to the most careful criticism by many generations of scholars and philosophers; but there is no general consensus on some important questions, and the possibility of misinterpretation is open. This is as a rule not true in the case of philosophers like Plato and Aristotle, whose work survives either completely or in bulk.

The main theme to be picked out is the one emphasized by Plato, in the passage of the Phaedo that we discussed in chapter 2: the explanation of the world in terms of matter in motion. We must begin, however, briefly, at the beginning: that means, with the three philosophers who lived in the sixth century b.c. in the prosperous Greek colony at Miletus, on the coast of Asia Minor – Thales, Anaximander, and Anaximenes.

The value of logos

The course of the history of philosophy and science was utterly changed by these two men. Many would claim, in fact, that philosophy in the modern sense began with Parmenides – or at least that a historian of philosophy today must begin with Parmenides. Earlier writers are now represented by a few isolated phrases or sentences of their own words and some garbled second-hand reports; but by great good fortune – and the far-sighted wisdom of Simplicius, who understood the historical importance of being able to quote the original text, a thousand years after it was written – a substantial portion of Parmenides' argument survives, in his own poetic words. It is undeniably an argument and undeniably philosophical; and its importance can hardly be exaggerated. Often in history, and especially in the history of science, although each progressive step is credited to the account of a single person or group, it can be seen that if the advance had not been made then, it would inevitably have been made soon by someone else. In the case of Parmenides, this is not true. There is nothing quite like his argument: it seems startlingly original.

Nevertheless, there is a point in including Heraclitus with Parmenides in the same chapter, although they were separated physically from each other by the whole of the Greek world – Heraclitus lived in Ephesus, Parmenides in the South Italian town of Elea – and they wrote in different genres.

When I first came to Rome I found certain physicians who avoided phlebotomy so sedulously that sometimes even when a person was suffocating from plethos they refused to use the remedy. In the case of a woman almost twenty-one years old, who had a red face and a slight cough and already some difficulty in breathing, as a result of suppression of the menstrual catharsis, I found them lightly binding her limbs with woollen bandages and ordering her to fast, but neither using phlebotomy themselves nor permitting me to do so. Since they were more trusted than I was because of their intimacy with the woman's family and their seniority, I gave up for the time being the attempt to convince them concerning phlebotomy; I did, however, enquire whether there would be any objection to provoking a flow of blood to the uterus by means of drugs with the power to effect this. When they agreed, I at once sought out the patient's usual midwife and urged her to make use of them. She told me, however, that she had used them as the occasion demanded, when the monthly purgation was expected to occur, and mentioned the drugs she had applied to the woman; they were all of approved quality, so that no one could think the treatment had failed because of their weakness.

It seems to me to be a question well worth investigating, why on earth Erasistratus, who was, after all, so competent in the other branches of the Art, and so meticulous about the minutest detail as to describe even the boiling of certain vegetables and of plasters – matters on which it would have sufficed any one else just to say what was essential and to omit the mode of preparation, as a minor point which anyone could pick up as he went along – why Erasistratus, in the case of such a powerful and important remedy as phlebotomy, and one that was esteemed by the ancients as in no way inferior to the most effective of all, has nothing to say. The fact is that the word K148 phlebotomy is scarcely to be found in any work of his; the one exception is in his book on bringing up blood, but even here he mentions it more, it would seem, in passing than as something he was considering with the care it deserves.

Galen (c. ad 129–200) was a Greek from Pergamon in Asia Minor. Because of his habit of putting autobiographical details into his works, we know that he was the son of a prosperous architect, Nikon, who named him Galenos (mild), perhaps in the hope that he would turn out different from his mother, who was a shrew. He speaks of his father with respect; he gave him an excellent education in literature, philosophy and the sciences, and finally sent him to Alexandria to study medicine after being advised in a dream to make him a physician. After a spell in Pergamon as medical officer to the gladiators, Galen went to Rome in 162 and quickly established a large and fashionable practice; the second bloodletting work gives a lively account of how he did it. It was not long before he was attending the emperor Marcus Aurelius, who had, if we can believe Galen, some very complimentary things to say about him. Galen wrote a short work, That the Best Physician is also a Philosopher, in which he condemned the ignorant and materialistically-minded doctors of his time, and urged physicians to emulate Hippocrates, who, at least according to Galen, had despised possessions and the pleasures of the table and the bed, and laboured unceasingly in the pursuit of knowledge.

No attempt at an exhaustive analysis of the writers between Hippocrates and Galen will be made here. Only a few will be considered; the aim is merely to illustrate the divergent opinions that were prevalent.

Whether or not Celsus was himself a physician, and whether his work is his own or a translation of a lost Greek original, it is of the greatest value in reconstructing medical opinion between the Hippocratic writers and Galen. In addition to many incidental references he devotes a chapter to venesection, which opens with the significant remark: ‘It is not new to let blood by cutting a vein; but that there is hardly any disease in which blood is not let, is new.’ This is, in effect, Galen's indication from the severity of the disease, regardless of its nature; his primary indication for bloodletting is the presence, or indeed only the expectation, of any severe disease whatsoever. According to Celsus this was in his time – some two centuries before Galen, unless he is reproducing an earlier work – a new concept. It cannot be Hippocratic, since Celsus describes Hippocrates as ‘the most ancient author’. As we have seen, the idea appears in the Corpus only in the Appendix to Regimen in Acute Diseases, which most scholars think spurious, although Galen says that this particular statement is good Hippocratic doctrine; this does not apply, however, to everything else in the treatise. It has already been shown that the Hippocratic writers used venesection far less extensively than Galen did, though Galen would like us to think otherwise; Celsus confirms this opinion.

It has been shown in the previous chapter that although the Hippocratic writers unquestionably made use of venesection, they mention it only briefly and in passing, neither offering a rational explanation for its use nor listing the indications. Galen is more systematic. From a study of all his references to venesection it is possible to extract a good deal of information on his practice, and to determine not only what he did but also sometimes why he did it. His indications will be considered first.

In brief, Galen regards venesection as an evacuant remedy to be used in certain patients with plethos, though not in all. Suppression of wonted evacuations of blood, such as the menses or bleeding piles, may lead to plethos, which in turn, if not dispersed, may result in inflammation. Apart from these considerations, any severe disease is an indication for venesection, not only when established, but even when foreseen or expected; thus venesection may be used prophylactically in healthy subjects. Galen employs the remedy widely in fever. It is further used as a revulsive or derivative remedy, to direct blood away from or towards a particular part; and a number of pathological conditions are specifically mentioned in which it is applied. These indications will now be considered in more detail.

As an evacuant, Galen says, venesection is selective; it empties only the veins, whereas starvation leads to the evacuation of the whole body, a process attended with many troubles for the patient. Besides, venesection acts at once, whereas starvation is slow and the weakest of all evacuant remedies; Galen remarks later that it does not evacuate directly at all.

In the foregoing chapters Galen's opinions on venesection have been collected from his surviving works and compared with the views of the Hippocratic writers and of some of his other predecessors and contemporaries. What has not been resolved, and probably cannot be certainly decided at all, is the origin of Galen's opinions. Although he has a profound respect for Hippocrates, his opinions on venesection are Hippocratic only in the sense that they are those of a fictitious Hippocrates whom Galen has constructed for himself. Although the seeds of his ideas are to be found in the Corpus, they have grown by the time of Galen into something far bigger and more organised than is found in the Hippocratic writings. It is not clear where and when this growth took place. Although Celsus, like Galen, makes more extensive use of venesection than the writers of the Corpus do, his practice is in many ways quite different from Galen's, and the same can be said of Aretaeus, Antyllus and Soranus. What, then, was the origin of Galen's peculiar methods and beliefs? They are not truly Hippocratic, and a study of a few surviving sources between the writers of the Corpus and Galen suggests that they were far from universal among practitioners of ability and reputation. Where, then, did they come from, and why did he hold them so tenaciously?

This question might best be answered with another: Why did Galen succeed in his practice?

An aim of this work has been to examine, not only Galen's opinions on bloodletting, but also the reasons why he held them; it is therefore necessary to consider whether he could have been justified in believing what he did. Galen, like most other practitioners of his time, used phlebotomy as an evacuant remedy in a great variety of diseases; he also employed it as a revulsive in a way that would seem quite incompatible with his knowledge of anatomy, yet which can be shown to have been justified in the light of the knowledge of his time. Is there any scientific justification for his use of venesection as a general evacuant, taking into account that the conditions under which Galen practised were different from those now prevailing? The arguments to be put forward would not be accepted by all authorities today; it is nevertheless however possible for a professional haematologist, making use of discoveries in medicine in the last thirty years, to put up a case of sorts for Galen's use of venesection as an evacuant remedy. Any such retrospective evaluation must, of course, be highly speculative. Two separate arguments can be used; one concerns resistance to infection, while the other is rheological. Infection will be considered first.

Most physicians today, if asked whether there were advantages to the patient in being anaemic, would probably not be able to think of many. And although most would certainly agree that degenerative disease of the heart and arteries is less prevalent in the undernourished, the orthodox view is that impaired nutrition makes for greater susceptibility to infectious disease.

This work originated from an interest in the history of ideas in medicine. I wanted to find out why our forefathers, almost to a man, believed that the proper way to treat most diseases was to remove blood from the patient, and as there was to my knowledge no published translation of Galen's three bloodletting works in any modern language, I made one from the Greek of Kühn's edition, and went on to consider where his ideas came from and how they developed in the course of a long and active life. The material was used in 1978 as a dissertation for the degree of M.A. in classics from the University of Natal. Subsequently the translations have been revised, and the discussion rewritten to make it more accessible to the general reader. An introductory chapter on Galen's system of pathology, based on subsequent reading, has been added, and the passages quoted in the text in Greek and in modern languages other than English have been translated. Although unfamiliar old terms are explained when first encountered, they have all been collected into a glossary for easy reference, together with such modern technical terms as may be unfamiliar to the non-specialist.

Kühn's text is corrupt in many places, and only one of the three works has had any critical attention. I have therefore examined a number of the manuscripts and early printed editions, which clear up some of the difficulties. I must make it clear, however, that the only aim has been to improve the translations, not to establish texts; I am not a philologist, even by inclination.