=Greek Coins.=--The character and provenance of the earliest coins agree with the best ancient tradition of their origin, in so far as it associates them with Asia Minor, although it is more probable that they were invented by the Greek cities of the coast than by the Lydians, to whom they have been credited in accordance with the Herodotean tradition.[8] The most primitive pieces are found in Asia Minor, and their metal is a natural mixture of gold and silver, called electrum, which occurs in the mountains of Lydia, and was brought down to the sea in the sands of the great rivers, the golden Hermus and its tributary the Pactolus. The cities which the Greeks had planted on the Asiatic shores grew in the seventh century B.C. to a high degree of wealth, by reason of their position on a rich coastland, where they were intermediary in the trade of east and west. There were great bankers in these Ionian cities who had large stores of treasure; their gold and silver would be kept in bars or ingots of definite weight stamped with the device, in place of the written signature, of the banker. From thus marking large ingots with his own signature, it would be a short step for the banker to do the same with smaller denominations of the same weights, so producing a private coinage for his own convenience in calculation, which would come to have a limited acceptance in the quarters where his credit was good. Such pieces are probably to be recognised in the nondescript coins of which the electrum stater is an example (No. =24=; fig. 12_a_); this is scored on one side with parallel scratches and stamped on the other with three deep punch-marks. There are many pieces in existence which have even less design than this, although their weights conform to definite coin-standards. We may perhaps regard this example as a private coin, one of the last of its kind, which immediately preceded the adoption of coinage by the state. The invention of coinage lies really in this innovation, which, however obvious it may seem to us now, was then of deep political significance. When once a state currency was instituted, the private coinage fell out of use, for no individual banker could compete with the guarantee of the state, and the state would not tolerate imitation of its own types. We may therefore take it that the successive stages in the "invention" of coinage were somewhat as follows: first, the occasional practice of stamping certain weights of metal with marks by which they could be identified; this probably continued in private use for a long period before it was adopted by a state; and finally the adoption all over the Greek world of a series of state coinages.