This anecdote is interesting, not only as it discloses the simple expedients for numeration and counting of time then practised, but also as it illustrates the geographical ideas prevalent. Darius did not intend to come back over the Danube, but to march round the Mæotis, and to return into Persia on the eastern side of the Euxine. No other explanation can be given of his orders. At first, confident of success, he orders the bridge to be destroyed forthwith: he will beat the Scythians, march through their country, and reënter Media from the eastern side of the Euxine. When he is reminded that possibly he may not be able to find the Scythians, and may be obliged to retreat, he still continues persuaded that this must happen within sixty days, if it happens at all; and that, should he remain absent more than sixty days, such delay will be a convincing proof that he will take the other road of return instead of repassing the Danube. The reader who looks at a map of the Euxine and its surrounding territories may be startled at so extravagant a conception. But he should recollect that there was no map of the same or nearly the same accuracy before Herodotus, much less before the contemporaries of Darius. The idea of entering Media by the north from Scythia and Sarmatia over the Caucasus, is familiar to Herodotus in his sketch of the early marches of the Scythians and Cimmerians: moreover, he tells us that after the expedition of Darius, there came some Scythian envoys to Sparta, proposing an offensive alliance against Persia, and offering on their part to march across the Phasis into Media from the north,[500] while the Spartans were invited to land on the shores of Asia Minor, and advance across the country to meet them from the west. When we recollect that the Macedonians and their leader, Alexander the Great, having arrived at the river Jaxartês, on the north of Sogdiana, and on the east of the sea of Aral, supposed that they had reached the Tanais, and called the river by that name,[501]—we shall not be astonished at the erroneous estimation of distance implied in the plan conceived by Darius. [500] Herodot. vi, 84. Compare his account of the marches of the Cimmerians and of the Scythians into Asia Minor and Media respectively (Herodot. i, 103, 104, iv, 12). [501] Arrian, Exp. Al. iii, 6, 15; Plutarch, Alexand. c. 45; Quint. Curt. vii, 7, 4, vii, 8, 30 (vii, 29, 5, vii, 36, 7, Zumpt).