They are really hollow concretions of an iron stone, containing a piece of loose iron or hardened sand, or a concretion of some kind that rattles, and is called by the Italians _bambino_ or “babe.” Such concretions are found at many places on every continent, many fine ones having been found in Delaware. They vary in size from one to six inches across. The small ones of a hard, smooth exterior that have become polished from wear, are especially valued as charms.[355] A passage in the treatise on stones by Theophrastus, pupil of Aristotle, might seem to indicate that the _ætites_ was already known in the third century B.C. The words he employs are as follows: “The most astounding and greatest power of stones (if indeed this be true) is that of bearing progeny.” As both Pliny and Dioscorides name this stone or geode and fully describe its character, laying especial stress upon the loose, rattling material enclosed in its hollow interior, this fact giving rise in later time to the half-poetic name of “the pregnant stone,” there is every reason to believe that it was already known of three or four, or even more centuries before their time.[356] Marbodus of Rennes calls this stone “the guardian and defender of nests.”[357] Enclosing as it did one or more smaller stones, it was thought to be symbolically designated as an aid to parturition. According as it was attached to the left arm or to the left thigh, it either retarded or accelerated the natural processes. This, however, by no means exhausted the virtues of the stone, for when worn on the left arm of man or woman, it conferred sobriety, increased riches, and moved the wearer to love; it also brought victory and popularity, and preserved children from harm. In addition to all its other powers this stone seems to have possessed a certain detective quality, to judge from the following words of Ætius, who wrote in the sixth century A.D.:[358] The ætites serves to discover thieves, if anyone places it in the bread which they eat; for whoever has committed a theft is unable to consume the bread. It has also been stated that, if cooked with any kind of food, the ætites unmasks thieves, since they cannot eat such food. If taken with wax from Cyprus, with fresh olive oil, or with any other calefacient, this stone greatly helps those suffering from rheumatism and paralysis. [Illustration: Ætites. From Johannis de Cuba’s “Ortus Sanitatis,” Strassburg, 1483. ]