EXPRESSION OF STYLE. 1115 good whole with it as when it is placed against a right-angled building, or where the jjediment over it forms the termination of a roof. For the same reason, a dome rising from a square base, or seeming so to do, is never so pleasing as one obviously forming the termination of cylindrical walls. The Architect, therefore, must have constantly in view the production, and the critic the discovery, of unity of system and principle, unity of conception and composition, miity of plan and elevation, unity of decoration, unity of style and taste, unity of the nature of the materials of which the building is composed, and unity even in the age, the. colour, and the appearance of those materials. This fundamental principle of criticism the Architect ought to keep continually in view ; not that the knowledge of this or of any other principle will insure his success in com- jiosition ; but that, having a composition before him, or in progress, the principle o{ unity is one of the very best by which he can test what he has done, or proposes to do. To the critic this principle is also of more value than any other, from the great ease and certainty with which it may be applied. 2205. Variety. In order to keep aUve in the human mind an interest in any subject, it is necessary that it should be operated upon by alternate excitement and repose. Now, as unity, wlien carried to its utmost limits, degenerates into monotony, the introduc- tion of contrasts into every composition is necessary for the purjiose of relieving it, and producing vai-iety and harmony. "N'ariety differs from harmony in having reference more to the details of the different component parts of a biulding, than to the eflFect of the building as a whole. Both variety and harmony are produced bj- contrast ; but liarmony, implying a greater combination of parts, admits of more numerous and powerful contrasts. (See Harmony, § 2217.) To produce variety in any composition, a certain degree of contrast becomes requisite in the lines, forms, colours, light and shade, and even, sometimes, in the nature of the materials. In introducing contrasts, the dangers to be avoided are, too great feebleness on the one hand, in which case they lose their effect, and produce insipidity ; or, too great opposition on the other, when their effect is too powerful, and they produce discords. Discordance of form is one of the most conspicuous faults in Architecture ; because, form being the principal attribute of matter with which the artist works, an error in this important feature of his composition is greater than one in lines, in light and shade, or m the nature of the materials. The introduction of contrasts, for the purpose of producing variety, is not only liable to end in discord, but it is also apt to degenerate into diversitj'. Diversity differs from variety, much in the same manner as complexity does fi-om intricacy. Variety may be produced by a few kinds of lines and forms varied in their disposition, but always with a certain degiee of connection ; diversity is produced by many different kinds of lines and forms, also differently disposed, but having no leading principle of connection, and so little accordance among themselves as not to compose a whole. In attempting to produce variety, therefore, by the only mamier in which it can be done, viz. the introduction of contrasts, the artist must be on his guard against creating discord, by having his contrasting forms of too large a size ; or diversity, by having them too numerous, and of too many difftrent sizes and shapes. For example, if to add some variety to the outline of a building, in ■nhich a square tower arose above the roof, a circular tower were added beside it, of the same height and general size, the effect would be discord ; because the two objects, being of the same kind, of the same bulk, and at the same distance from the eye, would present equal claims to attention : while, from the total difference of their forms, that attention would be divided. Let, however, the circular tower either be of the same diameter as the square cne, and raised only a few feet above the roof; or, let it be of the same height as the square one, and only a few feet in diameter, and the effect will be variety ; because the attention will be then directed to the large tower, and the very low or very narrow one will not interfere with the claims of the large one. At the same time, the small tower, by being something different from the large one, will also excite a certain though less degree of attention, and thus occasion a vaj-ied exercise of that faculty. To show how diversity or complexity may be produced under similar circumstances, we have only to suppose that, instead of one tower, several were added, all of diflerent forms, and all of the same size, and equidistant. They would, consequently, have all equal claims on the attention, which woidd thus be distracted ; and the mind would be unable to trace anv principle of order, by which so many different forms could be reduced to a whole. 2206. Intricacy is produced by number joined to variety, by which a certain degree of concealment is effected. It is a beauty chiefly sought for in the details of ornaments but sometimes also in the composition of elaborate elevations, or in extensive interiors. The opposite of intricacy is confusion, into which this beauty is in continual danger of degenerating. To prevent this, a certain degree of unity of system, and unity of forms and lines, must pervade the whole composition ; the same forms must frequently occur, and also the same manner of connecting them. " Nothing," says Alison, " is more delightful than, in any subject where we at first perceived only confusion, to find
