As to simplicity, he observes, that “a multitude of objects crowding into the mind at once, disturb the attention, and pass without making any impression, or any lasting impression; and in a group, no single object makes the figure it would do apart, when it occupies the whole attention. For the same reason, even a single object, when it divides the attention by the multiplicity of its parts, equals not, in strength of impression, a more simple object comprehended in a single view: parts extremely complex must be considered in portions successively; and a number of impressions in succession, which cannot unite because not simultaneous, never touch the mind like one entire impression made as it were at one stroke.
“A square is less beautiful than a circle, because it is less simple: a circle has parts as well as a square; but its parts not being distinct like those of a square, it makes one entire impression; whereas, the attention is divided among the sides and angles of a square.... A square, though not more regular than a hexagon or octagon, is more beautiful than either, because a square is more simple, and the attention less divided.
“Simplicity thus contributes to beauty.”
By regularity is meant that circumstance in a figure by which we perceive it to be formed according to a certain rule. Thus, a circle, a square, a parallelogram, or triangle, pleases by its regularity.
“A square,” says Home—(who here furnishes the best materials to a more general view, because he most frequently assigns physical causes, and whom, with some abbreviation, I therefore continue to quote)—“a square is more beautiful than a parallelogram, because the former exceeds the latter in regularity and in uniformity of parts. This is true with respect to intrinsic beauty only; for in many instances, utility comes in to cast the balance on the side of the parallelogram: this figure for the doors and windows of a dwelling-house, is preferred because of utility; and here we find the beauty of utility prevailing over that of regularity and uniformity.”
Thus regularity and uniformity contribute to intrinsic beauty.
“A parallelogram, again, depends for its beauty on the proportion [or relation of quantity] of its sides. Its beauty is lost by a great inequality of these sides: it is also lost by their approximating toward equality; for proportion there degenerates into imperfect uniformity, and the figure appears an unsuccessful attempt toward a square.”
Thus proportion contributes to beauty.
“An equilateral triangle yields not to a square in regularity nor in uniformity of parts, and it is more simple. Its inferiority in beauty is at least partly owing to inferiority of order in the position of its parts: the sides of an equilateral triangle incline to each other in the same angle, which is the most perfect order they are susceptible of; but this order is obscure, and far from being so perfect as the parallelism of the sides of a square.”