Incapacity of material.—It is evident at a glance that clay lacks the capacity to assume and to retain many of the details of form found in antecedent vessels. This necessarily results in the alteration or omission of these features, and hence arise many modifications of original forms.
The simple lack of capacity on the part of the potter who undertook to reproduce a model would lead to the modification of all but the most simple shapes.
The acquisition of the art by a superior or an inferior race, or one of different habits would lead to decided changes. A people accustomed to carrying objects upon the head, on acquiring earthen vessels would shape the bases and the handles to facilitate this use.
Improvements in the methods of manufacture are of the greatest importance in the progress of an art. The introduction of the lathe, for example, might almost revolutionize form in clay.
As arts multiply, clay is applied to new uses. Its employment in the manufacture of lamps, whistles, or toys would lead to a multitude of distinct and unique forms.
The acquisition of a new vessel-making material by a nation of potters and the association of the forms developed through its inherent qualities or structure would often lead ceramic shapes into new channels.
Fig. 473.—Coincident forms.