Each form of unity has its difficulties and dangers, which must be avoided if perfection is to be attained. In harmony there may be too much identity and too little difference or variety, with the result that the whole becomes tedious and uninteresting. This is the fault of rigid symmetry and of all other simple geometrical types of composition, which, for this reason, have lost their old popularity in the decorative and pictorial arts. In balance, on the other hand, the danger is that there may be too great a variety, too strong an opposition; the elements tend to fly apart, threatening the integrity of the whole. For it is not sufficient that wholeness exist in a work of art; it must also be felt. For example, in Pre-Raphaelite paintings and in most of the Secession work of our own day, the color contrasts are too strong; there is no impression of visual unity. In the dramatic type of unity there are two chief dangers--that the evolution be tortuous, so that we lose our way in its bypaths and mazes; or, on the other hand, that the end be reached too simply and quickly; in the one case, we lose heart for the journey because of the obstacles; in the other, we lose interest and are bored for want of incidents. We come now to the second great principle of aesthetic structure-- Dominance.[Footnote: Cf. Lipps: _Aesthetik_, Bd. I, S. 53, Viertes Kapitel] In an aesthetic whole the elements are seldom all on a level; some are superior, others subordinate. The unity is mediated through one or more accented elements, through which the whole comes to emphatic expression. The attention is not evenly distributed among the parts, but proceeds from certain ones which are focal and commanding to others which are of lesser interest. And the dominant elements are not only superior in significance; they are, in addition, representative of the whole; in them, its value is concentrated; they are the key by means of which its structure can be understood. They are like good rulers in a constitutional state, who are at once preeminent members of the community and signal embodiments of the common will. Anything which distinguishes and makes representative of the whole serves to make dominant. In a well-constructed play there are one or more characters which are central to the action, in whom the spirit and problem of the piece are embodied, as Hamlet in _Hamlet_ and Brand in _Brand_; in every plot there is the catastrophe or turning point, for which every preceding incident is a preparation, and of which every following one is a consequent; in a melody there is the keynote; in the larger composition there are the one or more themes whose working out is the piece; in a picture there are certain elements which especially attract the attention, about which the others are composed. In the more complex rhythms, in meters, for example, the elements are grouped around the accented ones. In an aesthetic whole there are certain qualities and