The maintenance of a complete and harmonious unity of object and purpose in the conduct of the representation, is a matter of essential importance in artistical composition of each kind, and contributes alike to the perspicuity of the de-sign, and to its general vigour and effect. This rule is applicable alike to delineation and to composition; but it is more essential in the latter than in the former, as there are both more independent parts requiring to be united, and from their greater variety there is more danger of their being disunited and acting discordantly in composition than in delineation. As one principal figure should always stand out as the foremost, so one main design should ever be obvious, to which all subordinate purposes should contribute and lend their aid. If the attention of the mind is divided, the perception is confused, and the impression much weakened. Hence, the union together of the different parts of a composition is an essential principle to be kept in view. It is, indeed, alone by this means, that all the various figures and groups become amalgamated into one whole; that they are made in reality to constitute a composition, instead of remaining independent objects.
Unity of design in composition is analogous to unity of purpose in action, and is essential to give effect and vigour to the design or representation. If the current is diverted, it loses its strength, and the various streams which meander through the country have nothing of the force which they would possess when united into one vast torrent. So is it in artistical composition of each kind. In Michael Angelo’s ‘Last Judgment, the result is much weakened by this want of unity of subject, which is indeed the great defect of the picture, although the unity of purpose is still preserved; and to the observance of this principle, Raphael’s renowned cartoons owe much of their force and effect.
Although several distinct representations may be aimed at by the different groups in the picture, as is the case indeed in the cartoons ; yet the effect, the general impression produced by the whole, should be one and the same. Here all the streams should meet, and should concentrate their forces. An epic poem may have many episodes; yet they should not only unite in one story, but all conduce to add effect to the main narrative which it contains.
Unity is essential alike to a design in painting or sculpture, a description in poetry or eloquence, a composition in architecture, music, costume, or gardening, and a dramatic representation. In each case the main channel of ideas must be kept open and clear, although a certain number of episodes may with advantage be introduced along with it. The lesser streams, however, should feed, not drain the main river ; and should also maintain a part so subordinate as to be always clearly distinguishable from it, although they ought at the same time to preserve their connection with it.
The various figures and parts in a composition should, indeed, be so united as to be each essential constituents of that composition, as well as related to one another ; and each should moreover be necessary to the place which it fills. If a figure or a metaphor may as well be in one part of the composition as another, it may probably be as well out of it altogether.
As all the different branches, however varied or diverging, are part of the same tree, so all the different figures in a representation are portions of the same composition. By preserving the unity of the subject the whole intent of the composition is evinced at once, and thus all our ideas are directed in the proper course. In every composition the entire design should appear to be directed to one object, to proceed from one mind, and to be of the same character.
Moreover, as distraction of the mind is ever displeasing, and what the mind always appears especially to shun, and as the promotion of gratification is, on the other hand, one of the leading objects of art; so disunity, which is particularly calculated to promote the former, should be ever avoided.
But there is a governing principle in composition as regards the union and harmony of parts, not only in groups but in single figures, and not only in figures, but even as regards the parts of a figure ; as in the human countenance, in which the expression of the various features should be all harmoniously blended so as to produce one effect.
As in the case of variation of forms, so in an analogous manner in that of unity, it should be at the same time free from uniformity. It should be the unity of nature, not that of mechanism. It should resemble rather the unity in form of an animal or a tree, than the uniformity in shape of a piece of furniture, or of a machine. Here, as in many cases of ethics as well as art, the right line lies between the two extremes.
It is the province of correct judgment and true taste to guide us aright to this happy medium.