At what period the Greeks began to build vessels and to venture upon the waters washing their coasts and girding their numerous archipelagoes, is not known: it is certain, at any rate, that the commencement of navigation with them, as with all other nations, must be referred to a time much anterior to the ages of which we have any record. Long voyages are mentioned as having taken place at periods so early that they must be considered mythical. The first maritime adventure which lays any claim to authenticity, and the most celebrated in ancient times, is the expedition of the Argonauts to Colchis. Though this enterprise is by many learned authorities deemed fabulous, we shall nevertheless consider three points connected with it,--the probable era of the voyage, its supposed object, and the various routes by which the adventurers are said to have returned. The date of the expedition, if it took place at all, may be safely fixed at the year 1250 B.C. A theory propounded by Sir Isaac Newton would connect it with the year 937; but this is regarded with less favor than the earlier date. Its alleged object was the Golden Fleece; but what this was can only be conjectured. It is hardly likely that the people of that age would have been tempted by the prospect of commercial advantages by opening a trade with the Euxine Sea. It is quite as unlikely that they would have undertaken so dangerous a voyage for the purpose of plunder, better opportunities for which existed much nearer home. The supposition that the Golden Fleece was a parchment containing the secret of transmuting the baser metals into gold, and the opinion that the Argonauts went in quest of skins and rich furs, hardly require discussion. There seems, indeed, no adequate motive but a desire to obtain the precious metals, which were believed to be furnished in abundance by the mines near the Black Sea. Why these mines were symbolized under the appellation of a golden fleece it is not easy to say, and no satisfactory reason has ever been suggested. The most probable is that the gold dust was supposed to be washed down the sides of the Caucasus Mountains by torrents, and caught by fleeces of wool placed among the rocks by the inhabitants.