wood already by itself possesses a definite form and consists of separate lengths, more or less in the straight line, lengths which can be brought together into rectangular corners no less than those which are acute or obtuse, and in this way provide corner pillars, supports, cross-beams and roof. Stone, on the contrary, never at any time possesses a form so definite. In contrast to the tree it is a formless mass, which first must be intentionally isolated and worked upon, in order that it may fit in juxtaposition to or superposition on other pieces and so once more be brought together with such. It requires, in short, several processes before it receives the form and serviceableness which wood already possesses independently. Moreover, stone material, when it is used in great masses, invites rather excavations and generally speaking, being _ab initio_ relatively formless, is capable of every kind of form, for which reason it is rather the congenial material for the symbolical as also the romantic types of building, while wood, by reason of its natural form of straight stems, is demonstrably without mediation more serviceable to that more severe type of purpose and observance of rule, which is the fountain-head of classical architecture. In this respect the structure of stone is mainly predominant with the self-substantive type of building, although even among the Egyptians, in their colonnades bordered with plinths, other considerations supervene, which the structure of wood is able more readily and in the first instance to satisfy. Conversely we do not find that classical architecture restricts itself entirely to buildings of wood, but, on the contrary, where it is elaborated in conformity with beauty, executes its buildings in stone; but in such a way, however, that we are from a certain point of view still able to recognize in the architectural forms the original principle of the wood structure, if also from a further one definite relations attach which do not belong to that kind of building as such.