+6.+ Some historians of the Hannibalian war, when they wish to point out to us the causes of this contest between Rome and Carthage, allege first the siege of Saguntum by the Carthaginians, and, secondly, their breach of treaty by crossing the river called by the natives the Iber. But though I should call these the first actions in the war, I cannot admit them to be its causes. One might just as well say that the crossing of Alexander the Great into Asia was the _cause_ of the Persian war, and the descent of Antiochus upon Demetrias the _cause_ of his war with Rome. In neither would it be a probable or true statement. In the first case, this action of Alexander’s could not be called the cause of a war, for which both he and his father Philip in his lifetime had made elaborate preparations: and in the second case, we know that the Aetolian league had done the same, with a view to a war with Rome, before Antiochus came upon the scene. Such definitions are only worthy of men who cannot distinguish between a first overt act and a cause or pretext; and who do not perceive that a _cause_ is the first in a series of events of which such an overt act is the last. I shall therefore regard the first attempt to put into execution what had already been determined as a “beginning,” but I shall look for “causes” in the motives which suggested such action and the policy which dictated it; for it is by these, and the calculations to which they give rise, that men are led to decide upon a particular line of conduct. The soundness of this method will be proved by the following considerations. The true causes and origin of the invasion of Persia by Alexander are patent to everybody. They were, first, the return march of the Greeks under Xenophon through the country from the upper Satrapies; in the course of which, though throughout Asia all the populations were hostile, not a single barbarian ventured to face them: secondly, the invasion of Asia by the Spartan king Agesilaus, in which, though he was obliged by troubles in Greece to return in the middle of his expedition without effecting his object, he yet found no resistance of any importance or adequacy. It was these circumstances which convinced Philip of the cowardice and inefficiency of the Persians; and comparing them with his own high state of efficiency for war, and that of his Macedonian subjects, and placing before his eyes the splendour of the rewards to be gained by such a war, and the popularity which it would bring him in Greece, he seized on the pretext of avenging the injuries done by Persia to Greece, and determined with great eagerness to undertake this war; and was in fact at the time of his death engaged in making every kind of preparation for it. Here we have the _cause_ and the _pretext_ of the Persian war. Alexander’s expedition into Asia was the _first action_ in it. [Sidenote: and of the war with Antiochus.]