only great masses make the action of gravitation apparent and impressive in a high degree. But this confirms my view that the tendency and antagonism of those fundamental forces of nature constitute the special æsthetical material of architecture, which, according to its nature, requires large masses in order to become visible, and indeed capable of being felt. The forms in architecture, as was shown above in the case of the column, are primarily determined by the immediate structural end of each part. But so far as this leaves anything undetermined, the law of the most perfect clearness to perception, thus also of the easiest comprehensibility, comes in; for architecture has its existence primarily in our spatial perception, and accordingly appeals to our a priori faculty for this. But these qualities always result from the greatest regularity of the forms and rationality of their relations. Therefore beautiful architecture selects only regular figures composed of straight lines or regular curves, and also the bodies which result from these, such as cubes, parallelopipeda, cylinders, spheres, pyramids, and cones; but as openings sometimes circles or ellipses, yet, as a rule, quadrates, and still oftener rectangles, the latter of thoroughly rational and very easily comprehended relation of their sides (not, for instance, as 6:7, but as 1:2, 2:3), finally also blind windows or niches of regular and comprehensible proportions. For the same reason it will readily give to the buildings themselves and their large parts a rational and easily comprehended relation of height and breadth; for example, it will let the height of a façade be half the breadth, and place the pillars so that every three or four of them, with the intervals between them, will measure a line which is equal to the height, thus will form a quadrate. The same principle of perceptibility and easy comprehension demands also that a building should be easily surveyed. This introduces symmetry, which is further necessary to mark out the work as a whole, and to distinguish its essential from its
