Themistocles’ first speech consists of an argument; his second of a threat; but, as Herodotus points out, the second was delivered under the influence of the anger he felt at the injustice of the taunt which Adeimantos had hurled against himself and his countrymen. Never was anger more justifiable. The necessity for the removal of the population had been brought about by the fact that the Peloponnesian land forces at the Isthmus had made no preparation whatever to defend Attica during the time at which the fleet was at Artemisium. One part of the argument is very striking, because it is, perhaps, the only passage in Herodotus which gives an indication of what must have been of necessity the case,—the dependence of the Persian army on the fleet Themistocles points out to the Greeks that, if they keep the Persian fleet at Salamis, the Persian army can never reach the Isthmus, or even invade the Megarid. More he does not say on this point, because he evidently assumed that his hearers would understand him. If the situation be considered, the only interpretation which they could pit upon his words was that the difficulty of commissariat would, under those circumstances, be an insuperable obstacle to the Persian advance. #ORIGINAL AUTHORITIES.# Their army, after crossing Kithæron, had left the rich lands of Greece, the plains of Bœotia and Thessaly, behind it. It might, indeed, have reached the Isthmus; but the maintenance of it even for a brief period in a region which could afford but little sustenance, and which was peculiarly inaccessible by land from the North, owing to the interposition of the great and difficult ridge of Geraneia, would become an impossibility.[157] [Illustration: Map showing THE STRATEGICAL POSITION IN S. BOEOTIA, W. ATTICA AND THE ISTHMUS WITH PASSES OF KITHAERON, PARNES & GERANEIA London: John Murray, Albemarle Street. _Stanford’s Geographical Estab^t. London._ ] * * * * * _Note on the Authorities for the Account of Salamis._ It is impossible to enter upon the description of the battle of Salamis without giving some short explanation of the views on the subject which the author has thought fit to adopt, since they differ fundamentally from those which are put forward in the best-known modern histories of Greece. The historians of the last generation do not seem to have recognized that the details of the battle as given by Herodotus present any difficulty of a serious character. His account was accepted as correct, against all other extant evidence on the subject, which was treated as either worthless or of inferior authority. Apart from chance references in other writers, which are either mere commonplaces or historically valueless, the evidence available is supplied by four authors,—Æschylus, Herodotus, Diodorus, and Plutarch. Those who adopt Herodotus’ views regard the evidence of the other three authors as being, for various reasons, unreliable.