third type of unity appears in any process or sequence in which all the elements, one after another, contribute towards the bringing about of some end or result. It is the unity characteristic of all teleologically related facts. The sequence cannot be a mere succession or even a simple causal series, but must also be purposive, because, in order to be aesthetic, the goal which is reached must have value. Causality is an important aspect of this type of unity, as in the drama, but only because a teleological series of actions depends upon a chain of causally related means and ends. The type is of two varieties: in the one, the movement is smooth, each element being harmoniously related to the last; in the other, it is difficult and dramatic, proceeding through the resolution of oppositions among its elements. The movement usually has three stages: an initial phase of introduction and preparation; a second phase of opposition and complication; then a final one, the climax or catastrophe, when the goal is reached; there may also be a fourth,--the working out of the consequences of this last. Illustrations of this mode of unity are: the course of a story or a play from the introduction of the characters and the complication of the plot to the denouement or solving of the problem; the development of a character in a novel from a state of simplicity or innocence through storm and stress into maturity or ruin; the evolution of a sentiment in a sonnet towards its final statement in the last line or two; the melody, in its departure from the keynote, its going forth and return; the career of a line. As I have indicated before, each type of unity has its specific emotional quality. The very word harmony which we use to denote the first mode is itself connotative of a way of being affected, of being moved emotionally. The mood of this mode is quiet, oneness, peace. We feel as if we were closely and compactly put together. If now, within the aesthetic whole, we emphasize the variety, we begin to lose the mood of peace; tensions arise, until, in the case of contrast and opposition, there is a feeling of conflict and division in the self; yet without loss of unity, because, if the whole is aesthetic, each of the opposing elements demands the other; hence there is balance between them, and this also we not only know to be there, but feel there. The characteristic mood of the evolutionary type of unity is equally unique--either a sense of easy motion, when the process is unobstructed, or excitement and breathlessness, when there is opposition.