The physical means to this end was the control of the sea. The advantages of sea power in warfare, in enabling the holder of it to circumscribe according to his convenience the area of military action, as well as in facilitating mobilization, transport, and communications, were not perceived for the first time by the English Admiralty, much less by Clausewitz and Captain Mahan. They are stated in the clearest terms by a contemporary of Pericles.[27] Here is what he says: "The subjects of a power which is dominant by land have it open to them to form contingents from several small states and to muster in force to battle. But with the subjects of a naval power it is different. As far as they are groups of islands (and the whole world, we may remark in passing, is now simply a magnified Ægean Archipelago) it is impossible for their states to meet together for united action, for the sea lies between them, and the dominant power is master of the sea. And even if it were possible for them to assemble in some single island unobserved, they would only do so to perish of famine. And as to the states subject to Athens which are not islanders, but situated on the continent, the larger are held in check by need and the small ones absolutely by fear, since there is no state in existence which does not depend upon imports and exports and these she will forfeit, if she does not lend a willing ear to those who are masters of the sea. In the next place, a power dominant by sea can do certain things which a land power is debarred from doing; as, for instance, ravage the territory of a superior, since it is always possible to coast along to some point, where either there is no hostile force to deal with or merely a small body; and in case of an advance in force on the part of the enemy they can take to their ships and sail away. Such a performance is attended by less difficulty than that experienced by the army marching along the seaboard to the rescue. Again, it is open to a power so dominating by sea to leave its own territory and sail off on as long a voyage as you please. Whereas the land power cannot place more than a few days' journey between itself and its own territory, for marches are slow affairs; and it is not possible for an army on the march to have food supplies to last for any great length of time. Such an army must either march through friendly territory or it must force a way by victory in battle. The voyager meanwhile has it in his power to disembark at any point where he finds himself in superior force; or, at the worst, to coast by until he reaches either a friendly district or an enemy too weak to resist. Again, those diseases to which the fruits of the earth are liable as visitations from heaven fall severely on a land power, but are scarcely felt by the naval power, for such sicknesses do not visit the whole earth everywhere at once.... There is just one thing which the Athenians lack. Supposing they were the inhabitants of an island,