But besides these little circles of musical time, there are the greater returning periods, and the still more distinct choruses; which, like the rhimes at the end of verses, owe their beauty to repetition; that is, to the facility and distinctness with which we perceive sounds, which we expect to perceive or have perceived before; or in the language of this work, to the greater ease and energy with which our organ is excited by the combined sensorial powers of association and irritation, than by the latter singly. This kind of pleasure arising from repetition, that is from the facility and distinctness with which we perceive and understand repeated sensations, enters into all the agreeable arts; and when it is carried to excess is termed formality. The art of dancing like that of music depends for a great part of the pleasure, it affords, on repetition; architecture, especially the Grecian, consists of one part being a repetition of another, and hence the beauty of the pyramidal outline in landscape-painting; where one side of the picture may be said in some measure to balance the other. So universally does repetition contribute to our pleasure in the fine arts, that beauty itself has been defined by some writers to consist in a due combination of uniformity and variety: Zoonomia, Vol. I. Sect. XXII. 2. 1. Where these repetitions of form, and reiterations of colour, are produced in a picture or a natural landscape, in an agreeable quantity, it is termed simplicity, or unity of character; where the repetition principally is seen in the disposition or locality of the divisions, it is called symmetry, proportion, or grouping the separate parts; where this repetition is most conspicuous in the forms of visible objects, it is called regularity or uniformity; and where it affects the colouring principally, the artists call it breadth of colour. There is nevertheless, an excess of the repetition of the same or similar ideas, which ceases to please, and must therefore be excluded from compositions of Taste in painted landscapes, or in ornamented gardens; which is then called formality, monotony, or insipidity. Why the excitation of ideas should give additional pleasure by the facility and distinctness of their production for a certain time, and then cease to give additional pleasure; and gradually to give less pleasure than that, which attends simple exertion of them; is another curious metaphysical problem, and deserves investigation.