Sensations, images, perceptions, and so on, give rise to feelings, not only on account of what they are, but also and indeed chiefly because of their manner of connection, of succession, and of spatial relation. Colors which we regard as most beautiful separately may compose a carpet whose color scheme we dislike and call inharmonious; on the other hand, the most uninteresting gray dots may compose a beautiful design. A piece of music is beautiful not alone because of the clearness of the single tones, but chiefly because of the relations of these tones in melody, harmony, and rhythm. One principle is generally applicable to this class of feelings: a variety of mental contents is bound together into a unity for our perception and imagination. A multitude of unconnected things is not easily perceivable or thinkable; therefore it is unpleasant. A single thing, so simple that it cannot be analyzed into component parts, cannot occupy our mind for any length of time; it is tedious, unpleasant. A combination of variety and unity is able to keep us mentally busy without overburdening the mind; therefore it is pleasant. The general principle, however, admits of a great many different applications. The unity may consist, for example, in the similarity and regularity of arrangement of the pickets of a fence. The unity may consist in subordination of a number of equal elements to a dominating element, as the larger fence post taking the place of a picket at regular intervals, or the accented element in a rhythm. The unity may consist in organic unity of the elements of a living thing. It may be logical unity, as in a sentence or a lecture. Several of these and other kinds of unity may appear simultaneously in the same matter; and one of these unities may be subordinate to another, this again to another, and so on, as in a Gothic cathedral, a symphony, or a drama. Thus the variety and complication of the feelings based on the principle in question is immensely great, depending on all these unities, their harmonious relation or opposition, and the contents of impression or imagination directly. This complication is further increased by the conditions discussed below. 2. _Feeling Dependent on Association of Ideas_