However imperfectly we are now able to follow the geographical distribution of the subject nations as given by Herodotus, it is extremely valuable as the only professed statistics remaining, of the entire Persian empire. The arrangement of satrapies, which he describes, underwent modification in subsequent times; at least it does not harmonize with various statements in the Anabasis of Xenophon, and in other authors who recount Persian affairs belonging to the fourth century B. C. But we find in no other author except Herodotus any entire survey and distribution of the empire. It is, indeed, a new tendency which now manifests itself in the Persian Darius, compared with his predecessors: not simply to conquer, to extort, and to give away,—but to do all this with something like method and system,[429] and to define the obligations of the satraps towards Susa. Another remarkable example of the same tendency is to be found in the fact, that Darius was the first Persian king who coined money: his coin, both in gold and silver, the Daric, was the earliest produce of a Persian mint.[430] The revenue, as brought to Susa in metallic money of various descriptions, was melted down separately, and poured in a fluid state into jars or earthenware vessels; when the metal had cooled and hardened, the jar was broken, leaving a standing solid mass, from which portions were cut off as the occasion required.[431] And in addition to these administrative, financial, and monetary arrangements, of which Darius was the first originator, we may probably ascribe to him the first introduction of that system of roads, resting-places, and permanent relays of couriers, which connected both Susa and Ekbatana with the distant portions of the empire. Herodotus describes in considerable detail the imperial road from Sardis to Susa, a journey of ninety days, crossing the Halys, the Euphratês, the Tigris, the Greater and Lesser Zab, the Gyndês, and the Choaspês. And we may see by this account that in his time it was kept in excellent order, with convenience for travellers.[432] [429] Plato, Legg. iii, 12, p. 695. [430] Herodot. iv, 166; Plutarch, Kimon, 10. The gold Daric, of the weight of two Attic drachmæ; (Stater Daricus), equivalent to twenty Attic silver drachmæ (Xenoph. Anab. i, 7, 18), would be about 16_s._ 3_d._ English. But it seems doubtful whether that ratio between gold and silver (10 : 1) can be reckoned upon as the ordinary ratio in the fifth and fourth centuries B. C. Mr. Hussey calculates the golden Daric as equal to £1, 1_s._ 3_d._ English (Hussey, Essay on the Ancient Weights and Money, Oxford, 1836, ch. iv, s. 8, p. 68; ch. vii, s. 3, p. 103). I cannot think, with Mr. Hussey, that there is any reason for believing either the name or the coin _Daric_ to be older than Darius son of Hystaspês. Compare Boeckh, Metrologie, ix, 5, p. 129.