All the forces that architectural structures are calculated to withstand are static and dynamic, and their operation depends on purely mathemat ical principles. Hence the structures which subserve or oppose these forces have only statical functions, and the operation of these functions can give expression to geometrical forms only.
Laws of Proportion.—One of the most widespread laws of proportion is the division of every whole into three parts, of which the middle, or principal, is characteristic of the functions to be performed, the lower, or base, brings it into relation with its foundation, and the upper either furnishes a means of transition to the parts above or forms the ter mination. This law is true alike in grammar and in form. All na tions divide every structure into foundation, wall, and roof; every pil lar has its base, shaft, and capital, and only in lower or degenerate forms do we find one of these omitted or misplaced.' Analogies of Form.—We may also consider the law of languages as a law of Nature, and discover in the building up of its systems the closest analogy with those laws of Nature which have been previously shown to be of normal application to artistic creations. All our analogies for the gen eral arrangement and distribution of parts were found in a province where the absolute supremacy of a few fundamental laws holds all individual subjective creation in abeyance; so that the most perfect execution of a given task by the artist lay in the thorough identification of his ideas with the laws of Nature, and perfection depended in no degree upon individual ity, while now, in the construction of our building, we reach an acting principle which, though analogOns to an unalterable law of Nature, gives, like language, more room for individuality in fashioning details.
When once a command of language has been gained, the same idea can be expressed in many ways, its harmony and delicacy of expression depending upon the delicacy of perception possessed by the writer or the speaker. The same holds good in the language of form; here talent is all-powerful. In this province there is no direct rivalry with those omnip otent, infallible laws of Nature which bring the most gifted and clearest intellect to feel its weakness; here man's powers are fully fitted for his task.
Ornamentation.—After the proportioning of the details conies the artistic shaping of the decoration of the various members and surfaces— that is, the ornamentation. This follows close upon constructive detail, and is even in many cases merely a continuation of it. The presence, position, and style of the ornamentation have so great an influence upon the expression of the purpose of the constructive members that decoration is as important as constructive detail. This is evident even in the arrange
ment of ornament. Decoration enjoys special freedom in its forms, since it is not hampered by constructive limitations and does not add more material, but serves solely the aesthetic idea which determined the arrangement of the masses and the methods of construction and guided the proportionment of the members._ Ornamentation also belongs to the language of form, and its shapes can have no relation to the structures of Nature, since speech and the formulating of particular ideas are not Nature's aim. What we consider the ornaments of a plant, as the flowers and leaves, are so only to our eyes, but in reality are as necessary to the life of the plant as are the stalk and the roots. They express no aesthetic ideas save such as are subject ively created in the human mind. Of course a perfectly useless ornament is out of place even in an architectural structure; the question as to its presence is analogous to that regarding the flowers and leaves of the plant. The character and ideal purpose of the edifice must determine the quantity and position of the ornamentation, and in a perfect structure the quantity must be neither too great nor too small. Its usefulness or uselessness does not depend on the material aspect of the work, which is here less important, but always on the ideal. Nature has given creative power to man alone, and therefore art, which is a portion of the divine fire reflected in man, is purely human.
ayorative Forms.—If all parts which fulfil constructive needs express those needs by strongly-marked geometrical forms, and if these con structive forms may be less massive when the parts have less to sup port or to hold, it follows that the purely-decorative forms of ornamenta tion may follow at will all the forms that the intellect can grasp, that the eye can see or the mind imagine. It can choose intricate geomet rical combinations or derive its forms from the vegetable or animal king doms, even including that highest of animal forms, the human body. Even imaginary animal and vegetable forms have a right to be repre sented. All possible objects of surrounding existence—tools and weapons, books and instruments, even the mountains and valleys with their trees and buildings—furnish material for ornamentation; yet all this must be arranged in accordance with the spirit expressed in the edifice.