We must also add another consideration, and it is this: that in the time of Phidias it was necessary for a sculptor to do far more with his own hand than it is now. Modern facilities have greatly abridged the personal labor of the sculptor in marble or bronze. The present method of casting in plaster, which was then unknown, or at least unpracticed, enables the sculptor of our days to elaborate his work to the utmost finish, in its full size, in the clay model; and when this is completed and cast in such a permanent material as plaster, the workman has an absolute model, which he may, to a certain extent, copy with almost mathematical accuracy. The greater portion of the work may therefore be now committed to inferior hands, as it requires only mechanical dexterity and care; while it merely remains for the sculptor himself to finish the work in marble, and add such elaboration of detail and expression as he may desire. But in the time of Phidias this method was unknown; and the sculptor himself was forced to do a much greater part of his work in marble. In like manner, the modern method of casting in bronze is so admirable that the labor of the artist in finishing the cast is comparatively small; but in the earlier period of bronze casting, there is no doubt that the cast originally was far more imperfect, and the labor of the sculptor in finishing far greater. These facts will in some measure seem to account for the comparatively long time during which Phidias was engaged on his works. As there evidently was no full-sized and completely finished model of the Athena or Zeus for the workmen mechanically to copy, Phidias was forced to work out the details of his great works with his own hands, moulding and designing them as he went on; and this he was obliged to do, not in a plastic material like clay, but in the final material of his statue—whether gold, ivory, or bronze. Assistants of course he had, and undoubtedly they were very numerous. Plutarch tells us that the public works gave employment to carpenters, modelers, brass cutters and stampers, chiselers and engravers, dyers, workers of ivory and gold, and even weavers;[3] and some of these men certainly worked for Phidias. In fact, he used the hands of others as much as he could—as any sensible artist would; but a great part of his invention and work was carried on in hard and difficult materials, instead of being perfected in a facile clay, as it would be by a modern sculptor; and this carried with it, of course, a great expense of time and labor.