familiar Müller-Lyer illusion is another which should influence artistic treatment. The apparent length of line can be changed by changing the direction of the lines which diverge from it. (5) The classical instance of artistic correction for illusion is in the Greek temple.

The stylobate of the temple curves upward in the middle to correct the apparent sag in long horizontals with verticals resting on them. The entasis, or outward swelling of the column, prevents the somewhat concave appearance which rigidly upright lines would give. The axes of the columns converge a little at their tops, preventing any appearance of spreading apart.

There are many more optical illusions to which we are subject, and many other forms of the ones mentioned, but there has been enough said to show that optical illusion may have a very considerable influence in artistic work.

Union of Action with Repose. No artistic work should be composed wholly of active lines or wholly of resting lines; a design which gives nothing but excitement is apt to be wearing, while one which gives nothing but repose is apt to be dull. The eye in either case demands variety and relief. Here, too, we might speak of a balance as obtaining between stimulation and rest.

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This formula is adopted, indeed, by Puffer as the test of every kind of art. But if we adopt the conception of balance we fail to allow for the fact that some compositions may properly have more stimulative power and less rest in them than others. A more liberal formula would be the "union" of action with repose, leaving the amount of each indeterminate.

Adaptation to Conditions. An artist in creating new forms does not merely "design" them; he designs them for something, or in answer to some demand. A designer who is commissioned to decorate a specified surface finds himself confronted with specified limitations, within which he must work. His space is of a certain size and shape, and occupies a certain position in a building. The building itself is dedicated to certain purposes, and possibly it is desired that the design should illustrate some given conception, or commemorate a given event. All this looks at first like so much hindrance to the artist's imagination; but it becomes, in fact, suggestive to him of an arrangement of lines and figures which he would otherwise not have conceived. When working without a commission an artist must set up limitations for himself, must imagine himself into a situation from which suggestions may come. Just as, within a composition, some lines are the answer to others, so the composition as a whole is an answer to the situation or set of conditions. In yielding to these specific conditions and expressing them, the design becomes individual and gains specific character. In adapting his old images to new situations, in coöperating with new conditions, the artist produces something new. We should be able

to tell at a glance what kind of space a figure was designed for, whether for a square, a circle, a spandril, a lunette, etc. If it is possible to do this, then the design expresses its spatial conditions, and is adapted to them. A design, also, which lets one see the sentiment which prompted it, expresses and is adapted to another of its conditions.

READING REFERENCES

Ross: "A Theory of Pure Design."

CRANE: "The Bases of Design." "Line and Form."

DAY: "Pattern Designing."

BATCHELDER: "The Principles of Design."

POORE: "Pictorial Composition."

PUFFER: "Studies in Symmetry." Harvard Psy. Studies, vol. i. PIERCE: "Esthetics of Simple Forms." Psy. Rev., vol. i.

MARTIN: "An Experimental Study of Fechner's Principles of Esthetics." Psy. Rev., vol. xiii.

ROWLAND: "The Esthetics of Repeated Space Forms." Harvard Psy. Studies, vol. ii.

MUMFORD: "Oriental Rugs." Chapter on " Design."

CHAPTER XI

ARCHITECTURE

ARCHITECTURE, as distinguished from sculpture, painting and surface design is more readily recognized as a practical art. It serves to inclose and protect spaces for human use, and to support and "set" other works of art. To accommodate specific needs of private life, of civic life, of religious worship, etc., and at the same time to satisfy the general need of pleasing the eye, is the twofold purpose of the art of building. Architecture, like pure ornament, is not the imitation of an object, but is the object itself. Unlike pure ornament, it has special practical ends to fulfil. Notwithstanding its practical connection with life, architecture is known as an abstract art.

Architecture is Abstract. In the terminology of Hegel, art is the manifestation of the Idea (by which is meant the concrete world-process) to Sense. The earliest form of art is an imperfect one-sided presentation of the idea; it is symbolic and abstract. The chief form of art at this stage is architecture. Architecture, we may say, is abstract in that it is a less intimate and less flexible medium than some of the other arts for the portrayal of human emotions and events.

There is another sense, however, in which architecture is abstract, a sense which is more concerned with the actual structure of a building than with its ideal express

iveness. A structure is abstract when the masses and lines which compose it seem to proceed directly about their business, and to have the minimum of imitative intention or of unreasoned deviation from their purpose. The elements of artistic building are masses, spaces and lines, and these are abstractions from the visible universe as we experience it. A vertical shaft, for example, resembles in a sense many different natural forms; it is like the trunk of a tree, the stem of a flower, the leg of an animal, the body of a man. It resembles all these, and they resemble each other by virtue of standing upright and being able to carry a weight. Similarly, a horizontal beam resembles a tree-trunk laid down, or a long flat stone, or the roof or floor of a cave, and this simply because it spreads out from side to side and is proof against the weather. Both the vertical shaft and the horizontal beam represent the element which is common to a number of natural forms; they each embody the general characteristic of a group, of support on the one hand and covering on the other, without literally imitating any special member of the group. In this sense they are both abstract forms; they stand for the common or generic idea of the group. Simple geometrical figures like shafts and beams, though the feeling-tone which we connect with them is the result of all past associations with their like, are so far shaken free from particular circumstance that we do not have to think of them as really imitating anything or representing anything except the idea of support and protection. The primitive builder propped up or roofed over his shelter with what branches or stones he found at hand. But as soon as the ideas of roofing and of