For the carrying out of operations on the scale requisite for an expedition aiming at the reduction of Greece as a whole, the command of a land route was necessary. The carrying capacity of a ship of those days was so small that it would have been very difficult, if not impossible, to transport a force of the magnitude required _across_ the Ægean. The expedition of 490 represents in all probability the utmost that Persia could accomplish by sea transport, and that was merely directed against Athens and Eretria, and had as its _declared_ object the punishment of the only two states of European Greece which had interfered in the Ionian revolt. But the results of Megabazos’ campaign, if unsupported by other facts, would afford very inadequate evidence of a design on Greece. ◆H. iii. 138.◆ There is, however, a tale in Herodotus, the very telling of which by that historian argues strongly for its general truth. It is the story of Demokedes, the famous physician of Kroton, who, having been in the service of Polykrates of Samos, was captured by the Persians at the time of his murder, and after a series of adventures became court physician at Susa. #PERSIANS EXPLORE THE GREEK COAST.# About the time when Darius was starting for the Scythian expedition, this Demokedes had rendered a great service to Atossa, the wife of Darius, who, instructed by him, persuaded Darius to send him with an expedition to explore the coasts of Greece, with a view to the subsequent invasion of the country. ◆H. iii. 136.◆ Accompanied by some prominent Persians, Demokedes went down to Sidon in Phœnicia, where the expedition embarked on two triremes and set sail for Greece. They circumnavigated the land, keeping close to the shore, surveying the coasts, and making notes thereof in writing. “At length, having examined the greatest part of it, they proceeded to Tarentum in Italy.” What happened thereafter is not so important. Suffice it to say that, with the aid of the tyrant of Tarentum, Demokedes made his escape, and went to Kroton, whither the Persians followed. The Krotonians refused to surrender him. The Persians accordingly sailed back to Asia, but, “not having their guide, they did not attempt to explore Greece any further.” It is not necessary to recount the rest of their adventures. ◆H. iii. 129–138.◆ Herodotus closes the tale by remarking that they were the first Persians who came from Asia to Greece, and that they were spies. This tale, like other tales of the time, did not lose in the telling. It manifestly contains fanciful elements. But there do not, on the other hand, exist any grounds whatever for disbelieving its main details,—namely, that such an expedition was actually sent with a view to explore the lands of Greece, and in accordance with an intention to invade the country when the necessary steps for such an invasion had been taken.