One chief aspect of order in a work of art is unity; unity of some kind is necessary for our restful contemplation of the work of art as a whole, since if it lacks unity we cannot contemplate it in its entirety, but we shall pass outside it to other things necessary to complete its unity.
In a picture this unity is due to a balancing of the attractions to the eye about the central line of the picture. The result of this balance of attractions is that the eye rests willingly within the bounds of the picture. Dr. Denman Ross of Harvard University has made a most valuable study of the elementary considerations upon which this balance is based in his “Theory of Pure Design.” He sums up his results in the formula that a composition is of value in proportion to the number of orderly connections which it displays.
Dr. Ross wisely restricts himself to the study of abstract and meaningless forms. The moment representation is introduced forms have an entirely new set of values. Thus a line which indicated the sudden bend of a head in a certain direction would have far more than its mere value as line in the composition because of the attraction which a marked gesture has for the eye. In almost all paintings this disturbance of the purely decorative values by reason of the representative effect takes place, and the problem becomes too complex for geometrical proof.
This merely decorative unity is, moreover, of very different degrees of intensity in different artists and in different periods. The necessity for a closely woven geometrical texture in the composition is much greater in heroic and monumental design than in genre pieces on a small scale.
It seems also probable that our appreciation of unity in pictorial design is of two kinds. We are so accustomed to consider only the unity which results from the balance of a number of attractions presented to the eye simultaneously in a framed picture that we forget the possibility of other pictorial forms.
In certain Chinese paintings the length is so great that we cannot take in the whole picture at once, nor are we intended to do so. Sometimes a landscape is painted upon a roll of silk so long that we can only look at it in successive segments. As we unroll it at one end and roll it up at the other we traverse wide stretches of country, tracing, perhaps, all the vicissitudes of a river from its source to the sea, and yet, when this is well done, we have received a very keen impression of pictorial unity.