The principle of the arch was known in very early times to Pelasgians in Greece and to Etruscans in Italy, both of whom, no doubt, derived it from the East. But it was valued more for its utility in certain constructions than for its artistic quality, and Greek classical architecture knows nothing of it. It was freely used in Rome, and here its extraordinary effect of vital energy as a supporter of weight first began to be perceived. When Romanesque and Gothic architecture seized on this principle, the strength of stonework, heretofore essentially placid, leapt into vehement life and action. A Gothic cathedral is the expression of a war of mighty forces held in equilibrium by their own antagonism. Every part seems to threaten destruction to some other. There is, of course, a war of forces in a Greek temple also, but there the weight and thrust answer each other, as we have said, directly; a vertical column supports a horizontal architrave, and _must_ support it, for nothing can give way without crumbling to pieces. In Gothic building the counter-stresses meet indirectly, a dead weight or a thrust is met by the springing curve of an arch; the whole structure would fall to ruin were it not for something in the stone which is not mere solidity, which arises from something vital and energetic in the scheme of the structure. The expression of conflict, therefore, as compared with Greek architecture, is greatly intensified; the serenity of power has given place to the play of forces rushing into eager and often tempestuous action, and saved from being mutually destructive by the control of a far-seeing design.[182]