Polybius: The Rise of Rome to World Power (220-167 B.C.)
 Had previous chroniclers neglected to speak in praise of History in general, it might perhaps have been necessary for me to recommend everyone to choose for study and welcome such treatises as the present, since men have no more ready corrective of conduct than knowledge of the past. But all historians, one may say without exception, and in no half-hearted manner, but making this the beginning and end of their labour, have impressed on us that the soundest education and training for a life of active politics is the study of History, and that surest and indeed the only method of learning how to bear bravely the vicissitudes of fortune, is to recall the calamities of others. Evidently therefore no one, and least of all myself, would think it his duty at this day to repeat what has been so well and so often said. For the very element of unexpectedness in the events I have chosen as my theme will be sufficient to challenge and incite everyone, young and old alike, to peruse my systematic history. For who is so worthless or indolent as not to wish to know by what means and under what system of polity the Romans in less than fifty-three years have succeeded in subjecting nearly the whole inhabited world to their sole government a thing unique in history? Or who again is there so passionately devoted to other spectacles or studies as to regard anything as of greater moment than the acquisition of this knowledge?
 How striking and grand is the spectacle presented by the period with which I purpose to deal, will be most clearly apparent if we set beside and compare with the Roman dominion the most famous empires of the past, those which have formed the chief theme of historians. Those worthy of being thus set beside it and compared are these. The Persians for a certain period possessed a great rule and dominion, but so often as they ventured to overstep the boundaries of Asia they imperilled not only the security of this empire, but their own existence. The Lacedaemonians, after having for many years disputed the hegemony of Greece, at length attained it but to hold it uncontested for scarce twelve years. The Macedonian rule in Europe extended but from the Adriatic region to the Danube, which would appear a quite insignificant portion of the continent. Subsequently, by overthrowing the Persian empire they became supreme in Asia also. But though their empire was now regarded as the greatest geographically and politically that had ever existed, they left the larger part of the inhabited world as yet outside it. For they never even made a single attempt to dispute possession of Sicily, Sardinia, or Libya, and the most warlike nations of Western Europe were, to speak the simple truth, unknown to them. But the Romans have subjected to their rule not portions, but nearly the whole of the world and possess an empire which is not only immeasurably greater than any which preceded it, but need not fear rivalry in the future. In the course of this work it will become more clearly intelligible by what steps this power was acquired, and it will also be seen how many and how great advantages accrue to the student from the systematic treatment of history.
 The date from which I propose to begin my history is the 140th Olympiad [220-216 B.C.], and the events are the following: (1) in Greece the so-called Social War, the first waged against the Aetolians by the Achaeans in league with and under the leadership of Philip of Macedon, the son of Demetrius and father of Perseus, (2) in Asia the war for Coele-Syria between Antiochus and Ptolemy Philopator, (3) in Italy, Libya, and the adjacent regions, the war between Rome and Carthage, usually known as the Hannibalic War. These events immediately succeed those related at the end of the work of Aratus of Sicyon. Previously the doings of the world had been, so to say, dispersed, as they were held together by no unity of initiative, results, or locality; but ever since this date history has been an organic whole, and the affairs of Italy and Libya have been interlinked with those of Greece and Asia, all leading up to one end. And this is my reason for beginning their systematic history from that date. For it was owing to their defeat of the Carthaginians in the Hannibalic War that the Romans, feeling that the chief and most essential step in their scheme of universal aggression had now been taken, were first emboldened to reach out their hands to grasp the rest and to cross with an army to Greece and the continent of Asia.
Now were we Greeks well acquainted with the two states which disputed the empire of the world, it would not perhaps have been necessary for me to deal at all with their previous history, or to narrate what purpose guided them, and on what sources of strength they relied, in entering upon such a vast undertaking. But as neither the former power nor the earlier history of Rome and Carthage is familiar to most of us Greeks, I thought it necessary to prefix this Book and the next to the actual history, in order that no one after becoming engrossed in the narrative proper may find himself at a loss, and ask by what counsel and trusting to what power and resources the Romans embarked on that enterprise which has made them lords over land and sea in our part of the world; but that from these Books and the preliminary sketch in them, it may be clear to readers that they had quite adequate grounds for conceiving the ambition of a world-empire and adequate means for achieving their purpose.
 For what gives my work its peculiar quality, and what is most remarkable in the present age, is this. Fortune has guided almost all the affairs of the world in one direction and has forced them to incline towards one and the same end; a historian should likewise bring before his readers under one synoptical view the operations by which she has accomplished her general purpose. Indeed it was this chiefly that invited and encouraged me to undertake my task; and secondarily the fact that none of my contemporaries have undertaken to write a general history, in which case I should have been much less eager to take this in hand. As it is, I observe that while several modern writers deal with particular wars and certain matters connected with them, no one, as far as I am aware, has even attempted to inquire critically when and whence the general and comprehensive scheme of events originated and how it led up to the end. I therefore thought it quite necessary not to leave unnoticed or allow to pass into oblivion this the finest and most beneficent of the performances of Fortune. For though she is ever producing something new and ever playing a part in the lives of men, she has not in a single instance ever accomplished such a work, ever achieved such a triumph, as in our own times. We can no more hope to perceive this from histories dealing with particular events than to get at once a notion of the form of the whole world, its disposition and order, by visiting, each in turn, the most famous cities, or indeed by looking at separate plans of each: a result by no means likely. He indeed who believes that by studying isolated histories he can acquire a fairly just view of history as a whole, is, as it seems to me, much in the case of one, who, after having looked at the dissevered limbs of an animal once alive and beautiful, fancies he has been as good as an eyewitness of the creature itself in all its action and grace. For could anyone put the creature together on the spot, restoring its form and the comeliness of life, and then show it to the same man, I think he would quickly avow that he was formerly very far away from the truth and more like one in a dream. For we can get some idea of a whole from a part, but never knowledge or exact opinion. Special histories therefore contribute very little to the knowledge of the whole and conviction of its truth. It is only indeed by study of the interconnexion of all the particulars, their resemblances and differences, that we are enabled at least to make a general survey, and thus derive both benefit and pleasure from history.
(Polybius, The Histories 1.1-4.)