was the same--elements alike in duration, but different in accent or significance, were made to cohere in a group or form. Just as in verse the feet, or elementary metrical forms whose elements are single syllables of equal duration but unequal stress, are combined into lines, and later these lines into stanzas, so in music measures are combined in figures, and figures built up into phrases, and phrases into tunes. And as the diversity of the possible forms becomes greater and greater as we advance from foot to stanza, there being few forms of feet but many of stanza, so metrical form in music becomes more and more complex as it evolves, and though all music must be built out of dual or triple measures, it may be built into tunes of an infinite variety of pattern. Each new complexity, however, must be intelligible; it cannot be introduced until men have mastered the simpler groups out of which it is compounded. Beethoven's wondrously intricate texture, Brahms's soaring phrases, would be meaningless to us had we not inherited from thousands of ancestors a sense of the system of regular accents and duration on which their complexities are superposed. From the days, ages ago, when savages first beat a drum in simple march rhythm, up to to-day, when Brahms builds up his extraordinarily intricate fabrics, with their elaborate prosody, their «augmentation,» and «diminution,» and «shifted rhythm,» the evolution of metrical form has been single and continuous; each advance has been built on previous achievements. There are no dropped stitches in this kind of knitting. Metrical form, however, is not the only sort of form by which sounds can be combined. It is the natural organizing agent of Dance, which, as we have seen, develops out of the movements expressive of men's active impulses; but human nature has also its contemplative side, and this, expressing itself in vocal utterance, undergoes another sort of development and results in Song. What, then, are the means by which Song is defined, by which vocal sounds are organized into intelligible and memorable forms? Before we answer this question it will be well to consider for a moment a more general one. What, in general, is a form?