On one of the shelves in a certain museum lie two small boxes filled with earth. A low mountain in Arran has furnished the first; the contents of the second came from the Island of Barbadoes. When examined with a pocket lens, the Arran earth is found to be full of small objects, clear as crystal, fashioned by some mysterious geometry into forms of exquisite symmetry. The substance is silica, a natural glass; and the prevailing shape is a six-sided prism capped at either end by little pyramids modeled with consummate grace. When the second specimen is examined, the revelation is, if possible, more surprising. Here, also, is a vast assemblage of small glassy or porcelaneous objects built up into curious forms. The material, chemically, remains the same, but the angles of pyramid and prism have given place to curved lines, so that the contour is entirely different. The appearance is that of a vast collection of microscopic urns, goblets, and vases, each richly ornamented with small sculptured discs or perforations which are disposed over the pure white surface in regular belts and rows. Each tiny urn is chiseled into the most faultless proportion, and the whole presents a vision of magic beauty. Judged by the standard of their loveliness there is little to choose between these two sets of objects. Yet there is one cardinal difference between them. They belong to different worlds. The last belong to the living world, the former to the dead. The first are crystals, the last are shells.