We must now turn to the commercial weight system. As elsewhere, one of the chief commodities to come under such a system was copper, and the history of the weighing of this metal, as far as it can be learned, will be of great importance to us. Now we should naturally expect that at Athens, which had in later days but one standard for gold and silver, copper likewise would have been estimated on this unit. But, as a matter of fact, there were two distinct standards in use at Athens, as is proved by two weights preserved in the British Museum, the inscription on one of which is _Mina of the Market_ (ΜΝΑ ΑΓΟΡ), that on the other is _Mina of the State_ (ΜΝΑ ΔΗΜΟ). This mina of the market is the same as that called the _Commercial Mina_ on an Attic inscription[418], where its weight is given as that of 138 silver drachms, that is, the weight of an Aeginetic mina of silver. Athens had not coined any money of her own up to Solon’s time, but seems to have employed the coins of Aegina. But this standard, although no longer employed for silver, did not fall into desuetude. As already pointed out, all peoples have felt the need of a heavier standard for cheap articles than that which serves for gold. Probably the Aeginetic mina had been used at Athens for copper: accordingly, when Solon made his new silver standard for the weighing of silver, the Aeginetic standard was found convenient for less costly and more bulky wares, and was therefore retained in use as the mercantile or market standard, the name STATE being given to the silver standard. We have learned already that in the early stages of society copper and iron are not sold or appraised by weight, but rather by measurement. We have also seen that there is every reason to believe that the Greek obol originally was a spike or rod of copper of a definite length and thickness. If we can believe the statement of Ephorus given by Strabo that Phidon of Argos established a weight as well as a measure system for the Peloponnesians (although Herodotus is silent as regards weights), it is not at all improbable that, taking this story in conjunction with the dedication of the old bar money by Phidon in the temple of Hera, we have here a genuine tradition of the superseding of the bars of metal, the value of which simply depended on their dimensions, by a system based essentially on weight. It is plain that, as copper was weighed both at Aegina and Athens by the Aeginetic silver standard, copper most probably was never estimated by weight until after the forming of the separate silver standard in the way already described.