SOURCE: "Thucydides," in Thucydides and the Science of History, Oxford University Press, 1929, pp. 14-34.

[In the following excerpt, Cochrane identifies Thucydides as a "scientific" historian, demonstrating that "Thucydides adapted the principles and methods of Hippocratic medicine to the interpretation of history" and further asserting that therein lies his "power and originality. "]

Ideas such as those enunciated by the Hippocratic school were unquestionably floating about in the Hellenic world as early as the middle of the fifth century B.C. Herodotus, for example, was well aware of the requirements of a genuinely scientific hypothesis, as he showed by his refusal to accept the theory of a 'stream of ocean', or any other figment of the poetic imagination, as an adequate explanation of the periodic rise and fall of the waters of the Nile. He also displayed familiarity with the theory that physical conditions determine human character, when he remarked, in his concluding chapter, as though to point the moral of his history, that 'soft countries are wont to produce soft inhabitants. It is impossible that the same land should yield an excellent harvest and men who are good in war'. Now if Herodotus had consistently made use of these principles as canons of historical interpretation, instead of introducing the religious or metaphysical principles which he actually employed, he might still have produced a great work, but it would have been an anticipation of Thucydides rather than the work which we actually possess. As it was, he frequently employed scientific standards both in the examination of fact … and in its interpretation.… The interpretation, for instance, of the Persian defeat at Plataea (ix. 62) as being the result of inferiority not in brains or strength, but in equipment and in the science of warfare, is quite 'scientific'. But it is when Herodotus comes to the ultimate questions of human history that he reaches an impasse; the reason being that he is unable to determine whether it is ultimately God or man who pulls the strings. This difficulty is illustrated by the passage (vii. 1-19) in which he discusses the causes of the Persian invasion. The physical causes having been expounded with great vigour and perspicacity, he finally turns from them as inadequate, and imports God in the shape of a nocturnal vision, to account for the act which Thucydides would have unquestionably referred to the love of domination and the prospect of power. If then, in the judgement, of moderns, Herodotus is inferior to Thucydides, it is not because he is a 'romancer'. That theory should long ago have been discarded. If we praise Thucydides and decry Herodotus at the present day, it is because our spiritual affiliations are with 'science' rather than with 'philosophy'; for Thucydides is the most scientific, as Herodotus is the most philosophic of Greek historians.

It has been thought necessary to depict at some length the background of Thucydides' thought for two reasons. Firstly, Cornford, in his brilliant and powerful argument, has referred the Histories to quite another setting. Secondly, the critics of Cornford, while they have put their fingers on what are without doubt the genuine characteristics of Thucydides, do not seem to have accounted adequately for the fact that those characteristics emerge in his work. Thus, in their hands, Thucydides himself appears as a portent, an 'uncaused' phenomenon in the stream of European thought. [J. B.] Bury, for instance, speaks of his 'powerful and original mind'; and a recent writer [G.F. Abbott, in Thucydides, A Study in Historical Reality, 1925] says: 'It is all the more to the credit of Thucydides that, living in an age when scientists still occupied themselves with problems altogether beyond the reach of scientific investigation, he did not allow his mind to wander into barren speculations, but kept it with unswerving steadfastness to those lines of thought upon which experience or deduction from experience could be brought to bear profitably. Upon these lines he concentrates his whole attention; and for the rest he has nothing to do but to take the universe as he finds it.' These critics go too far. In the fifth century B.C., at least in the one department of medicine, genuine science had emerged among the Greeks; and the power and originality of Thucydides lies in his having attempted to adapt the principles and methods of that science to the study of society.

There is no doubt that Thucydides, through his well-known connexion with the Thrace-ward regions, had at least the opportunity of meeting the Father of Medicine and becoming familiar with his work. That he actually did so is a probable inference from the close and, in some cases, startling analogies of style between the Histories and the Corpus Hippocraticum. These analogies have been noticed by most thoughtful students. Forbes, for instance, in his introduction to Thucydides i, recalls the penetrating observation of Littré [in Œuvres d' Hippocrate]: 'Thucydides lived and wrote at the same time as the physician of Cos; the more I have reflected on the style of the two, and sought to penetrate into its processes, its form, and its feeling, the more fully I am convinced that a close affinity existed between these writers.… It is to Thucydides that Hippocrates must be compared; in both we have a grave way of speaking, a style full of vigour, a choice of phrases full of meaning, and a use of the Greek language, which, although great pains have been taken with it, is nevertheless less flowing than that of Plato.' He then cites the Airs, Waters, Places (ch. xvi) as exhibiting these analogies of style.

It is our contention, however, that the analogy goes much deeper than mere style: that, in fact, Thucydides adapted the principles and methods of Hippocratic medicine to the interpretation of history; and to the demonstration of this the rest of this chapter must be devoted.

The commentators have noted that Thucydides was keenly interested in natural phenomena, and have collected examples of his observations, e.g. of eclipses, tidal waves, the whirlpool of Charybdis, the silting up of the Acheloüs mouth, volcanic action at Stromboli and Aetna, forest fires, and the effects of the plague on flora and fauna at Athens. They have further observed that in each and every case he sought a natural explanation of the phenomenon in question. But Herodotus had already, in his disquisition on the topography of the Thessalian plain, provided a model for the rational explanation of natural phenomena, when he remarked (vii. 129) that the gap at the mouth of the Peneius river is the work of an earthquake and consequently that those who like to call earthquakes the work of Poseidon may do so. Thucydides, therefore, cannot be credited with originality in this field; although one may notice in passing that his grip on the principle of the uniformity of nature is firmer than that of his predecessor. Herodotus, in default of a plausible natural explanation, may sometimes be tempted to take refuge in supernaturalism. Thucydides never yields to superstition. Ignorant, for example, though he be of the real causes of the solar eclipse, he is content to state the observable facts, that this phenomenon occurs only at the beginning of the lunar month; confident that the eclipse has no supernatural significance, and that in due course will be made the generalization which will explain the phenomenon to the satisfaction of scientif-ic minds (ii. 28).

The originality of Thucydides lies rather in his attempt to bring all human action within the realm of natural causes. In this connexion should be noticed the pecu-liar word πρόϕασως which he uses to designate a 'natural cause'. This word, which in Homer, Herodotus, and later writers unquestionably connotes 'formulated reason' or 'pretext', means in Thucydides 'exciting cause' or the 'physical antecedent of a physical state'. To Cornford πρόϕασως has proved a stumbling-block; it is one of the foundation stones upon which he builds his theory of Thucydides Myth-historicus. Other commentators, impressed with its apparently obvious meaning in Thucydides, have argued that, in this as in other cases, etymology must give way to common sense. The fact is that the word, as used by the historian, is in the highest degree technical. It is uniformly used by Hippocrates in the sense of 'exciting cause', and has been taken over directly by Thucydides in his attempt to apply the methods of medicine to history; the adaptation of methods involving, as is usual, the adoption of terminology.

In Thucydides, then, as in Hippocrates, it is assumed that all human actions and sufferings are subject to natural causes, and by these are meant the causes that are proper to human nature. In other words, both writers accept men no less than things as ultimates for the purposes of historical as of medical science. To Cornford this appears as a grave defect. He says: 'If we would understand Thucydides we must not regard a human action as partly caused by innumerable influences of environment, and by events that happened before the agent was born, right back into an immeasurable past.… The world upon which the Greek looked presented no such spectacle as this. Human affairs—the subject-matter of history—were not to him a single strand in the illimitable web of natural evolution; their course was shaped solely by one or both of two factors: immediate human motives and the will of gods and spirits, of Fortune, or of Fate. The rationalist who rejected the second class was left with the first alone—the original and uncaused acts of human wills.' The modern passion for reducing history to mechanics could hardly go farther than this. But surely Hippocrates and Thucydides are entitled, for the purposes of their science, to lay down their own postulates; and to admit if they so desire, specifically 'psychical' alongside of 'material' causes as ultimate factors for history. Again Cornford appears to go too far when he remarks that the ancients 'looked simply and solely to the feelings, motives, characters of individuals or of cities. These and (apart from supernatural agencies) these only, appeared to them to shape the course of human history.' The observations, quoted above from Airs, Waters, Places effectually dispose of such a view. To Hippocrates the ultimate factors were human motives in relation to environment, institutional as well as geographical. In his study of the evolution of Greek society at the beginning of the first book, Thucydides takes the cue and applies the Hippocratean principle to the elucidation of past as well as present, with such brilliance that the passage may truly be described as one of the greatest, as it is one of the earliest studies in human geography to be found in European literature.

To embark on a detailed examination of Thucydides' psychology would take us too far afield. It is sufficient to say that, like Hippocrates, Thucydides regards human nature as a relatively uniform and stable entity, in which, for purposes of analysis, one may distinguish … the intelligence which affords direction to the activities of the organism, and the various potentialities … which unfold in response to their respective stimuli, and result in various changes … which make for the well-being of the organism or otherwise. Here may be noted how modern is the psychology of Thucydides in contrast with the classical or 'faculty' psychology which was derived from Platonism, in that he stresses the unity of the organism in the response which it makes to any particular stimulus (iii. 45. 7). 'In a word then, it is impossible and absurd to suppose that, when human nature is subjected to a powerful urge in any direction, it can be diverted either by force of law, or by any other terror.' Again (iii. 45. 1), 'Yet carried away by hope, they take the risk of [rebelling against Athens]. No one ever condemns himself to death in advance, when he embarks on a dangerous enterprise'. This last passage illustrates how, according to Thucydidean psychology, judgement tends to reinforce desire, so that the resultant act is an act of the whole personality.

Thus personality counts as a factor in human history, and has to be taken into account in the explanation of events. Spontaneous combustion may account for forest fires (ii. 77. 4), but to explain the downfall of the Athenian Empire are needed the personalities of Cleon, Nicias, and Alcibiades, each of whom, in his own way, made his unwitting contribution to that catastrophe. Thucydides therefore parades them across the stage, not in order to abuse them or praise them, still less to gratify the idle curiosity of the casual reader with a mirror of statesmen, but simply in order that he may bring out the facts and ideas connected with them which are relevant to the analysis upon which his eye is steadily fixed.

On the other hand, the growth of society is no more spontaneous than its destruction. As Hippocrates had said, growth is the result of shock which stimulates the mind and awakens it from stagnation. Such shocks, Thucydides observes, as though developing the Hippocratean thesis, are those that come from the struggle for control of the valleys, resulting in the successive organizations of power which culminate in the polis, or the clash of cultures resulting from invasion, or the fusion of immigrant with native as in the case of Thesean Athens. No less significant are the accumulations of capital, which suggest to their possessors all sorts of possibilities hitherto undreamed of; and the invention of ships and the art of navigation, which constitute the foundations of historical Greece. In all cases, where new ideas are involved, it is assumed that these ideas were born in somebody's brain. Thus Ameinocles of Corinth appears as the man who invented the trireme and later introduced it into Samos. Similarly with the idea of consolidation.… In Athens this did not come about spontaneously, but was the work of Theseus, a man of power as well as wisdom. Theseus, stimulated by the existence of perils which arose not merely from foreign incursions but also from mutual quarrels among the village communities in Attica, and working by means of persuasion mingled with force, imposed on the inhabitants of the peninsula a unitary organization which afterwards got the sanction of religion; and deserved it, because indeed it saved the Athenians not only from foreigners but also from themselves. One is reminded of the observation of Hippocrates, quoted above, that there is an element of compulsion connected with nomos, but that nature ultimately comes in to reinforce it, so that it becomes indeed a sort of second nature itself. And one may suppose that consolidation, which was in Athens brought about as the response to certain conditions, came about in Argos and elsewhere, if not in response to the same conditions, at least to conditions equally compelling, or was introduced according to the self-same law of imitation which led the Samians to copy the naval architecture of the people of Corinth, and which to this day prompts progressive individuals and nations to import and adopt the advanced ideas of their rivals.

The power of innovation or 'invention' is one of the subjects which most engage the attention of Thucydides, and one which he discusses in various passages. In their speech at Sparta (i. 68-71), the Corinthians charge the Spartans with apathy and stagnation, and apparently attribute these defects of character to the peculiarity of the environment of Lycurgan institutions. On the other hand (70. 2) the Athenians are represented as innovators, quick to conceive an idea and to execute the plans which they conceive, beyond their powers daring, prepared to gamble beyond their judgment, in the moment of peril sustained by hope, venturing fearlessly abroad, etc.; so that (§9) in short, if one said that they were born neither to take any rest themselves or to allow it to other men, one would speak the mere truth. These characteristics, which constituted such a menace to the conservative states of Greece, are (71. 2) referred to the atmosphere and institutions of Athens. 'Your institutions,' the Corinthians say, 'compared with those of the Athenians, are out of date.'

The nature and purpose of the speeches in Thucydides must be reserved for later treatment. Meanwhile, it may be noted that Thucydides either shared with Pericles or was prepared to attribute to him a point of view substantially the same as that which he puts into the mouth of the Corinthians in the passage just quoted. In the Funeral Speech Pericles accounts for the unique qualities of his fellow citizens in precisely the same way, viz. as a result of the spiritual atmosphere created in Athens by the great generation to which Themistocles belonged, and maintained in ever increasing power and volume by their successors. The specific points which he makes, reminding one again of Airs, Waters, Places, are worth noting:

1. The Athenians are autochthonous, and the natural product of the peculiar geographical conditions in the Attic peninsula.
2. The shock of the Persian War gave Athens the first great impulse towards her imperial destiny. While Sparta and other conservative Greek states failed to rise to the occasion, and to effect those adaptations necessary to meet the new conditions created by the war, the empire-builders of Athens seized their opportunity and created the empire, which not without toil and stress they handed on to the succeeding generation.
3. The empire, as they possessed it, was the consequence of the atmosphere, social and political, of Athens.

With regard to the question of innovation—the capacity for conceiving and applying new ideas in human life—Thucydides in two passages, speaking in his own person, reveals his opinion. The first passage is in the estimate of Themistocles (i. 138. 3-6), the second, in the estimate of Pericles (ii. 65); and, of these, the former is the more significant. In the Funeral Speech also (ii. 37) it is argued that the spirit of equality in Athens is not inimical to distinction, that, in fact, so far from implying a cult of mediocrity, it actually makes provision for the employment of talent … wherever it may be found. The existence of talent—special endowment—Thucydides was prepared to recognize; whether it was the peculiar abilities of an Antiphon, or an Alcibiades, or even a Cleon, or the more normal qualities of a Demosthenes or a Brasidas, each of whom played his part in weaving the web of history, so that account has to be taken of him by the judicious historian. Accordingly, in the contribution of formative ideas to the life of the community, some men, such as Pericles and Themistocles, stood preeminently above their fellows. The latter, in whose fertile brain the idea of empire was first conceived, seems to have fascinated Thucydides. In estimating his contribution to Athenian life, he protested against the somewhat unfavourable verdict of Herodotus. Employing the current formulae of sophistic analysis, nature and nurture … , he reveals his belief that while nurture may save men from mediocrity, it can never account for genius. For the significance of Themistocles lay precisely in the revelation which he gave of the strength of natural genius. Without the advantages of a protracted education, but by the sheer force of his genius, he was in fact supreme in his ability to extemporize expedients to meet the necessities of the day. This is the answer which Thucydides makes to those (like Cornford) who complain that he makes too much of the 'uncaused actions of human will'. For history, talent—especially insight and penetration … —is, like human nature itself, original and ultimately inexplicable, a postulate in fact necessary to the science. Thus did Thucydides dispose of the question of mind in evolution; and his authority survived to create the psychological interpretation of history common to the greatest of subsequent classical historians. For us in our day it has remained to essay the task of dehumanizing the history of humanity.

Thucydides was a child of Periclean Athens, and the intense individualism of the age in which he lived made it natural for him, perhaps, to consider the problem of society and of history from the point of view of the relationship of individuals to the group. Accordingly, Thucydides is never tempted to conceive of society itself as an organism—and so far his point of view would meet with acceptance by 'realistic' sociologists of the present day. On the other hand, he was evidently impressed with the attempt in Periclean Athens to unify the interests and sentiments of the individual and the group, and he was no less impressed with the fatal failure to do so in the case, not merely of Alcibiades, but of the less spectacular conservative and ultra-reactionary landed classes with which he himself was connected. In one respect his individualistic prepossessions seem to have exposed him to the just criticism of the commentators, that is, in his account of the evolution of society in primitive Greece. The canons of interpretation which he employs in this field are exactly the same as he employs in his analysis of current history; and so he seems to have accepted the historicity of legendary figures like Agamemnon and Minos, the latter of whom, say How and Wells [in Herodotus,] he makes into a prehistoric Pericles. We may note in passing that he guards himself from dogmatism by referring constantly to the merely traditional character of his authorities. Nevertheless, in his reconstruction of early Greek history it is probable that Thucydides allowed himself to be carried away to some extent by the experience of his own day. A fifth-century Athenian could hardly have imagined a society like that of medieval Europe. He failed equally to appreciate the strength of the religious motive in the still undifferentiated society of primitive Greece. However, this at least is clear, that, in his treatment of prehistoric Greece, Thucydides fell victim to the formulation of an induction on too narrow a foundation of fact; for the individualism of the fifth century B.C. cannot be regarded as in any degree universal, though perhaps it is normal in developed societies. But it was not his method, so much as the inadequacy of the facts at his disposal, which was at fault.

The reconstruction of a past, remote whether in time or, more significantly, in spirit, may seem at best a hopeless task; and, as the real triumph of Thucydides lay in contemporary history, we gladly turn to his work in that field. The view of human motivation, which he appears to have held in common with Hippocrates, has already been examined. Beyond this, all belongs for the historian to the realm of τύχη or chance. Philosophy may, but science cannot know of 'any cause' capable of bringing to pass the plague in Athens at a critical moment in her history, or of any 'cause' capable of producing that fatal eclipse of the moon which completely immobilized the already terrified men of Athens at the last moment when escape was still possible from the hands of a vengeful and relentless foe. For history these are and must remain mere coincidences. Therefore, to those who accept the self-denying ordinance of history they must be relegated to the realm of … the incalculable. It is important to notice that in these, as in other cases, it is the coincidence itself which does not yield to any form of prognostication. Hippocrates (Airs, ii) had already remarked that the contribution of astronomy to medicine was anything but insignificant, on account of the effect which celestial events have on the diseases and the digestive organs of mankind. Similarly, the effect of the plague at Athens upon the morale of the Athenians is a proper subject of scientific investigation; and at the same time the plague itself is traced to a natural cause, in contagion, through the Piraeus from Egypt. The coincidence of events, however, remains inexplicable. Accordingly, while theologians and philosophers may dispute regarding the ultimate meaning of such coincidence, as Polybius does about the coincidences that in his day laid the Mediterranean world at the feet of Rome, or Sallust (in his letter to Caesar de Ordinanda Republica) about the coincidences that in their turn brought the Roman world beneath the heel of the dictator, the truly scientific historian, limited by his self-imposed method, can do nothing but hold his peace.

Scientific history, as Thucydides argues (i. 20-2), has nothing in common with imaginative literature, but consists in the diligent and unremitting search for truth, and it has its own standards of evidence … similar to the evidences of medicine, which are under favourable conditions adequate.… The truths of history like those of medicine consist first in the actual transactions which have taken place … ; and these, even if they are subjects of first-hand knowledge, should be accepted only after most careful check with the results of independent observations. Next come the λόγοι, or formulations—summaries and at the same time interpretations—in so far as these entered into and affected the course of events. With regard to the transactions themselves, Thucydides notes in true scientific fashion the common dangers to which the historian is exposed, the psychological perils arising from moral bias, defective recollection, as well as the carelessness and lack of observation characteristic of mankind. In the case of the λόγοι the difficulties of the historian are more acute.

For in the λόγοι, the permanently valuable elements of his work, Thucydides faced the problem, not merely of reporting correctly what was actually said on each occasion, but of amplifying and developing these statements in a manner appropriate to the occasion. To the modern historian, this may seem a strange kind of realism; actually in the hands of Thucydides this quaint literary convention, which Herodotus had carried over from the epic or the drama, affords an admirable vehicle for the expression of those points of view, always partial, frequently conflicting, which determined the transactions—the great issues, in short, of the war and the mainsprings of human action in relation thereto. The Funeral Speech then, and all the other speeches, represent the thought of Thucydides just as they are expressed in language which is unquestionably his own. But in another sense they are genuinely objective, in so far as each of them constitutes an analysis conveying to the reader the attitude of representative individuals or groups in relation to the facts which came up for discussion. To state the facts and formulate the issues, this appears to have been the aim of Thucydides. Thus he was almost always enabled to avoid dogmatic judgements in his own person. And if the facts are well authenticated and the points of view are fairly and adequately represented, the device enables the historian to withdraw from the picture, leaving the reader to judge for himself. If this was Thucydides' aim, he appears amply to have achieved it, as witness the controversies which in modern times the commentators have waged regarding the significance of the war.

The λόγοι, therefore, represent the attempt of Thucydides to do for history what Hippocrates was at the same time trying to do for medicine—the attempt, that is, to establish such classifications or formulations (τὰεζδη) as would raise history from the level of mere chronicle, characteristic of the annalists just as in medicine the same formulations were needed if medical science was to escape from the mere empiricism of the Cnidian school. Through the symptoms to arrive at a general description and thence to penetrate, if possible, to the true classification of the malady, this is the procedure which Hippocrates advocates and which he designates by the words semeiology and prognosis. But this was the very process which Thucydides sought to apply to history, which thus for him becomes the semeiology and prognosis of human life.

The unforgettable picture of the plague at Athens, copied by Lucretius and imitated by Procopius in ancient, as it was by Gibbon in modern times, has always been accepted as one of the best illustrations of Thucydides' temperament, the keenness with which he observed concrete fact, the cold detachment with which he reported the symptoms of a malady to which he himself had fallen victim, the precise analytical power with which he portrayed the changes, not merely bodily but also mental, of the disease. For the commentators generally the account of the plague has illustrated these characteristics. For us it does more; it constitutes the most intimate link between Thucydides and Hippocrates, and seems indeed to be the bridge between the two.

In his account of the plague Thucydides follows precisely the Hippocratic procedure. After the general introduction (ii. 47-8), in which he describes the outbreak and its gravity, he begins (49) by what in Hippocratic terminology is a κατά στασις— a general description of the conditions, climatic and otherwise, prevailing during the summer in which the plague broke out. Then follows the general description of symptoms, including a reference (§6) to the fact that the 'crisis' occurred as a rule on the seventh or ninth day. Now there is no feature of Hippocratic theory more striking than this notion that every malady tends to run a normal course up to a crisis, which once surmounted, the patient normally recovers. So Thucydides, having dealt with the course of the disease up to its crisis, goes on (§6-7) to describe what may be called the complications attending recovery. Such, he concludes, is the general description or semeiology of the epidemic. With regard to its classification or prognosis, unfortunately no rational account can be given. For, contrary to normal experience, the affliction spread to beast and bird, and also (51.2) there was no specific remedy, so to speak, the application of which assured relief. Then, too, it smote all alike (51. 3) whatever had been their medical history or their regimen of life. Thus this epidemic eluded rational classification from every point of view. The passage incidentally throws light on the Thucydidean conception of πρόγνωσς what is 'classification' and how is it possible?

Hippocratean prognosis, after the general description of symptoms, usually includes an account of psychical reactions. In his attempt, indeed, to relate psychical manifestations to the physical constitution, Hippocrates is generally credited with having developed the theory of the four primary humours, of health as a blending of these in due proportions relative to the organism, and of disease as a disturbance, normally resulting from a failure in the process of assimilation. Accordingly, Thucydides proceeds to record the depression and hopelessness that settle down on the patient, when the presence of the disease is detected, as well as his vain elation when the crisis is successfully passed, and the hope, scientifically groundless, that he would never perish of any other disease. He notices also the effect of the situation upon those who, themselves not having as yet fallen victims, either feared to approach the sufferers, or if they did so, paid the penalty of their unselfish idealism (51. 5) with their lives.

In the Hippocratean sense, the plague was an unparalleled shock, and likely therefore to be the occasion of derangements equally unparalleled. Such was indeed the case, and (53) Thucydides goes on to describe the general outbreak of social anarchy and demoralization which was its result—an outbreak in which the most evil passions of human nature were released, and which human law proved as powerless as divine authority to check. Thus neither Hellenic religion nor Periclean statesmanship sufficed to provide safeguards adequate to meet the shock (§4).

The canons of interpretation employed for the prognosis of the plague seem to us to be the canons employed also in the interpretation of Greek history generally. For Thucydides, the evolution of society is determined by a principle which, in contradistinction, on the one hand to materialism, and on the other to idealism, we venture to designate as that of 'physical determinism' ('Physical', following the usage of Hippocrates and Thucydides. Modern usage perversely seeks to restrict the meaning of this word to that of 'the world with man left out'.). Logically, perhaps, following the classification of Aristotle, causes may be distinguished as 'material', 'formal', 'efficient', and 'final'; but it should be remembered that these distinctions had not yet been made when Thucydides wrote; and it may be questioned whether, from the point of view of historical interpretation, they were or are of any great value. For, from the standpoint of science, the kind of 'formal' and 'final' causes which have been employed have proved useless; because such causes are not susceptible of observation and verification by scientific procedure. But, in any case, science does not raise itself by its own bootstraps; and there is no possible demonstration, scientifically speaking, of the existence either of nature or of God. Natural causes there are, unless man is a madman living in a madhouse; and these are at one and the same time 'material' and 'efficient'. For example, when Thucydides attributes the beginnings of the city state to the accumulation of capital, he does not mean to imply that the 'material', whether it be land, cattle, slaves, or hard cash, is what determines the course of evolution. These things, to him, constitute capital in so far as their meaning and significance are appreciated by their possessors. In other words, he is thinking in terms analogous to those employed in the parable of the Talents. The man without a sense of the value of his possession buries it in the earth. His fellow, conscious of what may be done with his, puts it to work and makes it bear fruit. The just sense of value, which enables the prudent speculator to size up the situation and to manipulate with profit the forces at his disposal, is the same sense of value which Thucydides attributes to personalities like Themistocles and Pericles. Carlyle, exaggerating no doubt the significance of great personalities, turns history itself into the biographies of its great men. Thucydides is perhaps more judicious, and never forgets to relate genius to the circumstances which give it an opportunity for free play. Thus in another age Nicias, with his conventional morality, might have exercised a salutary influence on the fortunes of his country. As a politician, however, in democratic and imperialist Athens, and as the reluctant leader of her forces in an enterprise which he loathed, his very virtues proved pernicious and contributed to the disaster which he had sought so studiously to avoid. This is not to say that in politics there is no morality; yet it does imply that political situations may arise in which a man can be too moral, or rather that in certain situations the rules of conventional morality can with difficulty be applied. In such sit-uations, the advice of Plato is, characteristically, that the 'good' man should take refuge under the wall. In this connexion, the function of the scientist is to state the observable facts; while once more theologian and philosopher may speculate regarding the mysterious ways of Providence or Fate.

Thus, while Fate or Providence rewards each man according to his desert, the only 'moral' which the historian can draw is that it is necessary to cultivate that mysterious power of insight, which science postulates as a natural endowment of individuals and peoples. Thus the problem of the social physician becomes a problem of finding appropriate nourishment, we shall not say for the soul, but for the constitution of man; and we shall see in the following chapter how the problem of doing so is faced, as Thucydides sees it, by Sparta and Athens, and in each case with what observable results.

For it is noteworthy that in both cases the problem is faced, and that both the system of liberty and the system of authority are represented as positive prescriptions of a definite and intelligible regimen of life. Athenian liberalism, no less than Spartan authoritarianism, is far removed in spirit and in practice from the optimistic liberalism or anarchism of modern times. Neither Hippocrates nor, presumably, Thucydides ever supposed that 'nature', if left to herself, could work the miracle of cure.

He, however, who looks for a positive statement of Thucydides' own views on this subject, will look in vain; for the pages of Thucydides contain no readymade system of social therapeutics. Hippocrates had divided the work of the physician into three parts: semeiology, prognosis, and therapeutics. Semeiology and prognosis are really two aspects of the same process. They include at one and the same time the accurate observation and the intelligent appreciation of data. Thus the mechanical notion of 'induction', by which one is supposed first to collect the data and then to generalize from them, is not Hippocratic, and whoever of the moderns may desire to have the credit of discovering 'induction' may do so. To Hippocrates, as to Thucydides, it is obvious that if you set about collecting pebbles in order to make a generalization from them, you must have in your mind the rough idea of a pebble to start with, otherwise it may turn out that after all you have been collecting eggs or apples instead of pebbles. Thus the function of semeiology, and prognosis is simply to widen the connotation of the class or, in other words, it is not a mechanical and passive, but an active mental process, and this is what makes it a capacity which few in the highest degree enjoy, so that, exemplified in a Themistocles, it is a subject for admiration. Thus scientific history makes no attempt to rob life of its great mystery. It accepts the fact of natural endowment as an essential condition of well-being and progress; at the same time noting the comparative rarity of its occurrence in any very full measure; and the consequence for mankind of those great inventions which spring from the brains of its possessors.

The scientific historian, as such, limits himself to the semeiology and prognosis of society; leaving to the political philosopher the task of constructing, on the basis of this prognosis, an adequate system of social therapeutics. This, then, is the real reason for many of the peculiarities of Thucydides which the commentators have noted and for which they have tried to account. His 'objectivity' and 'detachment' are results of the scientific method which he consciously adopts, and seeks conscientiously to apply. This, rather than the circumstances of his birth and life—his mixed descent, his affiliation with the conservatives, his exile by the democrats—enables him to characterize his native country, and put his finger with unerring precision on both the strength and weakness of imperial democracy. Moreover, his reticence is the reticence of relevancy. His duty is to consider the significance of personalities and events, in strict relation to his purpose. Hence those silences in regard to what happened, if the events had no bearing on the particular issue under discussion, which after all distinguish history from annals. Hence also those partial portraits or sketches of personalities, so vivid as far as they go, but yet so irritating to the modern, with his habit of discursive reading and of discursive writing. These, also, are in strict keeping with scientific method, and serve to distinguish history from biography. Finally, it is vain to look in the pages of Thucydides for any systematic statement of his beliefs. The good social physician will, in prognosis, keep strictly to the task of writing the 'history' of his patients, and he will reserve his schemes of social therapeutics for special treatment later, if he himself essays the task of treatment.

Yet, to all who accept the method of science, i.e. the view that life itself is the real teacher of mankind, so that it is necessary to consider how men do as a fact behave, before considering how they should, the one task is the necessary preliminary of the other. Such a conviction may without doubt be attributed to Thucydides; therein lies for him and for those who think with him the usefulness of history.

If this point of view be accepted, it limits decisively the scope and nature of social science. Sociologists, as such, should cease to look in history for anything except observable physical causes; and they should no longer attempt to extract from the study of society any general law of progress, as they have long since ceased to find in history any general law of decline, and as, in modern times, few or none of them profess to discover in it evidence for a law of cycles. To do otherwise is to violate the first principle of scientific method, as laid down by the author of Ancient Medicine, and applied by Thucydides to sociology—to confuse the 'is' with the 'ought'—in short, to disguise what is really philosophy in the gown of science. For it was against the general hypothesis that the author of Ancient Medicine had levelled the full weight of his artillery, seeking to demolish this citadel as the necessary preliminary to genuine science. It is both the right and the duty of science to speak in terms of limited and concrete ends. History, for instance, may properly consider the 'progress' of Rome under the principate in the direction of centralized and bureaucratic autocracy; or it may consider the decline of the city state from a condition of independence and self-sufficiency to that of a mere municipality under the imperialism of Alexander or of Rome. But to the questions: 'what constitutes progress or decline in general, how do these come about, and how may they be measured?' history returns no answer. These are general hypotheses, utterly unverifiable by observation; that is, they belong to the realm of philosophy, and not to the field of history and social science.

The word 'history' is full of ambiguity, and this is not surprising, because of the various senses in which the word is commonly used. We shall not speak of those to whom the record of the past is quite without meaning, although there is perhaps an increasing number of such. Apart from them, there are many people who regard history as a record once and for all delivered to the saints. For them, this record is sacred, and no considerations of truth are allowed to disturb the source from which they draw nourishment to feed their favourite prejudices. To others, history is merely material for propaganda. Unconscious, perhaps, of the sharp distinction between 'historical' and 'imaginative' literature, or, it may be, despairing of the possibility of an accurate interpretation of the past, they do not hesitate to 'reconstruct' history by the suppression of features which are unpleasant or disagreeable to them; and thus Clio is prostituted to the cause of world-peace, or progress, or whatever worthy or unworthy cause they desire to foster. There are, however, still others who follow Thucydides in regarding history as the diligent and unremitting search for truth, and who combine the most profound respect for the 'facts', in so far as these can be discovered, with the attempt to interpret these facts, as the physician endeavours to interpret the symptoms of his patient. To these history is really the equivalent of political science. In the present chapter we have endeavoured to set forth the method of this science as Thucydides saw it. In subsequent chapters we shall attempt to illustrate the fruits of the method, as he uses it for (a) the prognosis of power (social welfare as realized in state and empire), and (b) the prognosis of weakness, or the pathology of society. Besides illustrating certain results which the scientific method yields, this survey will perhaps serve to demonstrate its limitations, especially in relation to what may be described as the philosophical method of approaching the same profound questions.