These interruptions of the musical current, called Cadences, are generally so well defined that even the more superficial listener is made aware of a division of the musical pattern into its sections and parts, each one of which closes as recognizably (though not as irrevocably) as the very last sentence of the piece.
Cadences serve the same purpose in music, then, as do the punctuation marks in rhetoric; and an idea of the senselessness and confusion of a musical composition, if left devoid of cadences in sufficient number and force, may be gleaned from an experimental test of the effect of a page of prose, read with persistent disregard of its commas, colons, and other marks of "cadence." * * * * * * Another evidence of Form in music, that is at once subtle and powerful, rests upon what might be termed the _linear_ quality of melody.

The famous old definition of a line as a "succession of points," tallies so accurately with that of melody (as a "succession of single tones"), that it is not only proper, but peculiarly forceful, to speak of melodies as _tone-lines_.

Our conception of a melody or tune, our ability to recognize and reproduce it, depends far more upon its undulations, its rising, falling, or resting level, than upon its rhythmic features (the varying lengths of its tones).

These movements trace a resonant line before our mind's eye as surely, though perhaps not as distinctly, as the pencil of the artist traces the lines of an image upon the paper; and this process is going on constantly, from beginning to end, in every piece of music.

In a portrait it describes the contours of face and figure,--in a word, the _Form_; in the musical composition it fulfils, to a great extent, the self-same mission, that of defining the Form.