The _as_, having been once subjected to weight, its hundredfold, the _centumpondium_ or “hundred weight,” became the highest Roman weight-unit. Thus the _as_ and the _centumpondium_ of the Italians correspond to the mina and talent of the Greeks. But it will be observed that the Italians obtained their higher unit by the old decimal system, whereas the Greeks had borrowed the mina and its sixtyfold from Asia. The _centumpondium_ must be regarded as a true-born Italian unit, not one borrowed from Greece or Asia, and of this there is further proof. We saw by the ancient Roman law that the cow was estimated at 100 _asses_, the sheep at 10 _asses_. No doubt from time out of mind 100 of the bars of copper, which formed the chief lower unit of barter, made one cow, just as in Annam 280 little hoes make one buffalo (p. 167). When copper came to be weighed, the amount of copper which formed the equivalent of the highest unit of barter, the cow, was taken as the highest weight-unit. From what I have said above it is not improbable that the Roman libra and the Sicilian litra of copper were almost equal in weight. The fact that the Greek writers always employed the Sicilian word litra (λίτρα), to translate the Latin _libra_, likewise indicates that in the Greek mind there was a tradition of their identity. And if the doctrine here put forward of the original nature of the _as_ be right, nothing can be more likely than that the Italians who had crossed into Sicily and their kinsfolk who had remained behind employed rods of similar size, and that when they began to weigh the latter, the “weight” (libra or litra), derived from the standard copper rod, should be the same in each region, until certain modifications occasioned by new monetary conditions according to the needs of different communities had caused some divergency in _coin_ weights, although as a _commercial_ weight the litra remained unchanged. As Aristotle identified the Aeginetic obol and _chalcus_ with the Sicilian litra and _onkia_, we may with some plausibility suggest that the ancient Greek copper obol or spike and the Italian _as_ or rod were identical in dimensions and in origin. In Greece the copper obol rapidly fell in weight, for, when once silver currency had been introduced, copper was thrust aside, and it was not till the fourth century B.C. that copper coins came into use. When the copper obol appears as a coin it is but a small piece, being in fact a mere token. [Illustration: FIG. 50. As (_Aes grave_). (Before 2nd Punic War.)]