Conservatism of form makes itself felt in many cases in which an object is made of new material. The relinquishment of the old material may be due to lack of an adequate supply of the old material, or it may be an innovation due to an inner creative impulse. It constitutes a break with the past. The old forms, however, are often retained. Such substitutions are the more liable to occur the more plastic the new material. Pottery, to a lesser extent wood, and also stone are the principal materials in which forms can be imitated in the round. Particularly pottery lends itself readily to the manufacture of a great variety of forms. When the necessary skill in tempering the clay, in modeling and firing has been attained, the opportunity is presented for copying a great variety of forms. Thus we find shell dishes and spoons, gourd vessels and basket forms imitated in pottery. We still continue doing so. We have in our China ware innumerable instances of copies of even the finest fabrics. In Africa we find clay lamps which are evidently derived from the forms of bronze lamps of antiquity in which the complicated feet are imitations of wire work, and many pottery vessels seem to be copies of baskets. For instance, the handled ceremonial clay dishes of the Pueblo Indians look more like baskets than like pottery forms. On account of the great frequency of imitative forms in pottery the theory has been advanced, that all pottery forms must have originated from prototypes that were first made in some other technique. Professor Schuchardt[92] assumes that the first neolithic forms which are pointed at the base, must be copies of bottles made of hide. Cushing and Holmes[93] have advocated the theory that pottery and pottery designs developed from basketry, that pots were first of all modeled over a basket and that the basket with its clay cover was then fired. The basket was thus burnt and the clay vessel remained in the form of the basket. In corroboration of this theory it has been pointed out that actually clay covered baskets have been found, on the surface of which the ornamental pattern that is usually found on the basket is painted on the clay. These attempts do not seem to me convincing. The oldest pottery that we know is very crude and does not recall any other technical form. The Eskimo made clay lamps of unbaked clay that seems to be merely squeezed into shape. It seems much more likely that the firing of clay was discovered when foods were cooked on clayey soil or in pits in clayey ground, than that baskets should be made watertight by an application of clay and that the basket, the making of which is a laborious process, should then have been intentionally destroyed. However, I do not wish to introduce a new unproven theory in place of others. For our purpose it is sufficient to recognize the frequent copies of natural and technical forms in pottery. [92] Carl Schuchardt, Alteuropa, Berlin 1919, p. 44.