When Chaldæan civilization became sufficiently advanced for writing to be in widespread use and for every man to provide himself with his own personal seal, no great search for convenient materials was necessary. The rounded pebbles of the river beds gave all that was wanted. The instinct for personal adornment is one of the earliest felt by mankind, and just as the children of to-day search in the shingle of a beach for stones more attractive than the rest, either by their bright colours, or vivid markings or transparency of paste, so also did the fathers of civilization. And when they had found such stones they drilled holes through them and made them into earrings, necklaces and bracelets. More than one set of pebble ornaments has been preserved for us in the Chaldæan tombs. In many instances forms sketched out by the accidents of nature have been carried to completion by the hand of man (Fig. 129). They were not long contented with thus turning a pebble into a jewel. The fancy took them to engrave designs or figures upon them so as to give a peculiar value to the single stone or to sets strung into a necklace, which thus became a kind of amulet (Fig. 130). In the first instance this engraving was nothing more than an ornament. But one day it occurred to some possessor of such a stone to take an impression upon plastic clay. Those who saw the image thus obtained were struck by its precision, and were soon led to make use of it for authenticating acts and transactions of every kind. The presence of such an impression upon a document would perpetuate the memory of the man who put it there, and would be equivalent to what we call a sign manual. But even when it developed into a seal the engraved stone did not lose its talismanic value. In order to preserve its quasi-magic character, nothing more was required than the presence of a god among the figures engraved upon it. By carrying upon his person the image of the deity in which he placed his confidence, the Chaldæan covered himself with his protection as with a shield, and something of the same virtue passed into the impressions which the seal could produce in such infinite numbers. [Illustration: FIG. 129.--River pebble which has formed part of a necklace.] [Illustration: FIG. 130.--River pebble engraved; from De Gobineau.] No subject occurs more often on the cylinders than the celestial gods triumphing over demons. Such an image when impressed upon the soft clay would preserve sealed-up treasures from attempts inspired by the infernal powers, and would interest the gods in the maintenance of any contract to which it might be appended.[295] To all this we must add that superstitions, of which traces subsist in the East to this day, ascribed magic power to certain stones. Hematite, for instance, as its name suggests, was supposed to stop bleeding, while even the Greeks believed that a carnelian gave courage to any one who wore it on his finger.