Through Alexander, too, this mood was sponsored and written carefully into his history, for the leader of the Greeks' war of revenge needed his own historian, and with Aristotle's help, the man for this lucrative job had been forthcoming. Callisthenes, cousin of Aristotle, was already known among educated Greeks for his book on Greek Affairs from th e King's Peace to the Sacred War.He had worked with Aristotle and learnt from him, and they were jointly engaged on the compilation of a list of the victors in the Pythian Games at Delphi, a labour of chronological love which contrasted with their flighty disregard for historical fact in other more familiar writings. Callisthenes was a man with an academic turn of mind; he was interested in the origins of place names and had theories on the date of the fall of Troy; like his mentor Aristotle, he used early Greek poems as evidence for history; he had a knowledge of botany and geography and perhaps of astronomy too; he argued for the influence of the sea on earthquakes, and he supported his argument not only by his own observations but by the fact that Homer had called the sea-god 'shaker of the earth'. He knew his Herodotus well, as befitted an author who had to describe a march through Asia and he was through and through a man of Greek culture; in the lively controversy over the origins of the Egyptian Pharaohs of the Nile Delta, he sided with those who argued, absurdly, that their ancestor was an Athenian. Academic interests went, as often, with a decided streak of silliness, mostly in keeping with attitudes shared by Aristotle and his pupils: he explained away the outbreak of the Crisaean war by the absurdly personal cause of an heiress's abduction; he admired the repressive constitution of Sparta, a common opinion among Greek intellectuals who did not have to live there; he agreed with Aristotle in the myth that the philosopher Socrates had kept two wives; worse, he maintained that Aeschylus, greatest of Greek dramatists, had written his plays when drunk. When he wanted he could be perverse, but it never perturbed his conscience that his home town of Olynthus on the eastern borders of Macedonia had been ruined by the Philip whose son he now flattered. Through Aristotle, presumably, he had first come to court, and Alexander commissioned him to write up his exploits in a suitably heroic manner; he had already shown, like Aristotle, that he knew how to compose a panegyric, and he made himself welcome by helping to prepare Alexander's treasured copy of the Iliad.

'Alexander's fame,' Callisthenes is said, very plausibly, to have remarked, 'depends on me and my history,' This is true, and one of the difficulties in the search for Alexander is that this history only survives in some ten informative quotations by other authors. The literary models for such a work were more panegyric than historical and Callisthenes wrote in a rounded rhetorical style. The tone of his book was extremely favourable, for it was written to please Alexander, who was presented as the glorious equal of the gods, expressed in terms of the Greek culture which dominated Callisthenes's outlook. His starting point and end are unknown and he does not seem to have sent back his work in instalments to keep the Greeks informed. The theme of the Greek crusade was presumably stressed, although no surviving extract mentions it, and it was no doubt pleasing to Alexander that Callisthenes was thoroughly familiar with Homer's poems and well able to cap his feats of glory with quotations from the Iliad.'A man who is trying to write properly,' Callisthenes remarked, 'must not miss the character he is describing, but must try to fit his words to the man and his actions'; through his efforts Alexander can still be seen as he wished to be seen, and the wish is the nearest route to his personality. Other historians, whether officers or literary artists, would read Callisthenes to add to their factual outline, but they were not dominated by him; from facts which are common to them all, his history appears to have been a detailed and flattering report of Alexander's route and prowess, and not only personalities but also such statistics as enemy numbers and losses were wildly distorted to set off the achievements of the new Homer crusader. Callisthenes, in short, was the sponsor of Alexander's personal myth, and the search for Alexander is also a search for Aristotle's academic cousin.

For men faced with the invasion of Asia, these touches of heroic exaggeration were not altogether out of place. To Greeks who only knew the western coast of Asia Minor, the Lebanon and coastal Egypt, the conquest of Asia might indeed seem easier than that of Greece. In Persia's strictly graded society, even a minor nobleman could be called the 'slave' of his superiors, the king or the barons of the Seven Families. 'Man a

bandaka,my slaves' so the Great King addressed his satraps, but his empire had never been the slavish kingdom of an all-powerful master. Centralized rule is the victim of time and distance and in an empire where a royal letter could take three months to go from Phrygia to the Persian Gulf power had had to be local to avoid dilution by mountains and slow roads. The Greeks had watched the satrapies of western Asia become the privileged duchies of recognized families or the subject kingdoms of native rulers who knew the language, the local villagers and tribal chieftains of the ever-present mountains. It suited the Great King to allow the empire to pass to these local governors, each of whom bore no love for his neighbouring equals; it also seemed to suit an invader, who could play one interest off against another and travel through the empire on its own incoordination. But for an invader who meant to control his conquests, it was not so easy. When no one foundation supports the whole edifice of empire, the defeat of the centre is never final and freedom still flourishes in unrelated fringes.

To Persians the world seemed increasingly hostile the farther a man moved away from the circles of Parsa, his home province. As their court travelled ceaselessly from palace to palace in attendance on their itinerant king, they needed no reminder of the wearying presence of the empire's independent fringes. 'Taking a dry and hardened sheet of ox-hide he laid it on the ground and trod on one edge of it', men said of a Hindu philosopher who talked in India with Alexander's officers, 'and as it bunched together its other parts rose off" the ground. Then he walked round the rest of it, pressing hard on each comer to show how it had the same result, until he stood in the middle and the whole of the skin subsided. This was his way of proving that Alexander should press hardest on the centre of his empire and never stray far beyond it.' The Great King knew that the centre mattered most, but he was not prepared to give up his fringes without a fight. He had never recognized Egypt as an independent kingdom, although she had only submitted to the empire for the past seventy years. The Suez canal, creation of the Pharaohs, had become unusable and the seafaring kings of Cyprus and Phoenicia had a respectable history of recent rebellion; twice in Philip's lifetime the satraps and local dynasts of western Asia had threatened to desert the empire and once, even, to march down the Euphrates and take Babylon. Against each of these western dangers royal generals had been despatched to raise armies of varying enormity: after repeated, and sometimes spectacular, attempts, they had trampled the empire's fringes back into place. If the memory of revolt remained to help Alexander, western Asia had at least returned to its allegiance to the king.

The Persian concern for the west is not easily explained, except by the wish to retain an ancestral empire. As the middle kingdom between China and the Mediterranean, Iran does not have a natural interest in the Mediterranean sea; by Aegean observers, reared on memories of Persia's invasions of Greece, it was easily forgotten that the empire existed for its Iranians and they wanted three things of it. They wanted protection for their estates and country castles against the tribes of the mountains and forests and safety from the fearsome nomads of central Asia whom drought and the need for grazing might force across the Oxus or south from the Caspian Sea; they wanted a court with ceremonial which would mark out the unique majesty of their king and set him above his aristocratic circle of Honoured Equals. These ideals of security and ceremonial depended on food and precious metals, without which there could be no garrisons, no court honours; hence the high value of Babylon's Fertile Crescent from whose artificially watered farmlands a third of the court's yearly food and a mass of its raw silver were drained east to the Persians' palaces and to courtiers from the harsher world of the Iranian plateau. Even among the Greeks, who knew little of the Persians' eastern empire, there were those who thought the Euphrates or the rivers bounding Asia Minor to be the natural frontier of Persian rule. But the Persians had gone to great expense and trouble to disagree; the kings who had mounted huge expeditions against the west had allowed their former conquests in the Punjab to return to local rajahs, the lands beyond the Oxus to be governed by allied barons from forts of unassailable rock and all memories of Persian rule to fade on the lower course of the river Indus. But as long as Babylon's farmland was safe, Egypt, the fleets of the Levant and the cities of Greek Asia ought to have been irrelevant to the needs of an Iranian court.