not be determined arbitrarily, but by its end, and its relation to the whole. The column is the simplest form of support, determined simply by its end: the twisted column is tasteless; the four-cornered pillar is in fact not so simple as the round column, though it happens that it is easier to make it. The forms also of frieze, rafter, roof, and dome are entirely determined by their immediate end, and explain themselves from it. The decoration of capitals, &c., belongs to sculpture, not to architecture, which admits it merely as extraneous ornament, and could dispense with it. According to what has been said, it is absolutely necessary, in order to understand the æsthetic satisfaction afforded by a work of architecture, to have immediate knowledge through perception of its matter as regards its weight, rigidity, and cohesion, and our pleasure in such a work would suddenly be very much diminished by the discovery that the material used was pumice-stone; for then it would appear to us as a kind of sham building. We would be affected in almost the same way if we were told that it was made of wood, when we had supposed it to be of stone, just because this alters and destroys the relation between rigidity and gravity, and consequently the significance and necessity of all the parts, for these natural forces reveal themselves in a far weaker degree in a wooden building. Therefore no real work of architecture as a fine art can be made of wood, although it assumes all forms so easily; this can only be explained by our theory. If we were distinctly told that a building, the sight of which gave us pleasure, was made of different kinds of material of very unequal weight and consistency, but not distinguishable to the eye, the whole building would become as utterly incapable of affording us pleasure as a poem in an unknown language. All this proves that architecture does not affect us mathematically, but also dynamically, and that what speaks to us through it, is not mere form and symmetry, but rather those fundamental forces of nature, those first Ideas, those lowest grades of the objectivity of will. The regularity of the building and its parts is partly produced by the direct adaptation of each member to the stability of the whole, partly it serves to facilitate the survey and comprehension of the whole, and finally, regular figures to some extent enhance the beauty because they reveal the constitution of space as such. But all this is of subordinate value and necessity, and by no means the chief concern; indeed, symmetry is not invariably demanded, as ruins are still beautiful.