But this rule has its necessary exceptions; necessary because, as we have learned, the principle of Variety is quite as vital as that of Unity or symmetry.

The phrase is not always regular; by various means and for various reasons, it occasionally assumes an irregular form.

When such irregular phrases are encountered (phrases of less or more than four measures) the student will best distinguish them by defining their extremities, their beginning and ending--as "beginning" and "ending," without reference to their length.

This should not be attended with any serious difficulty; at least not to the observant student who reads his musical page thoughtfully, and attaches some meaning to the figures and motives of the melody; who endeavors to recognize the extent to which the successive tones appear to cling together (like the letters in a word) and constitute an unbroken melodic number,--and, in so doing, also recognizes the points where this continuity is broken, and a new number is announced.

Much assistance may be derived from the fact--striking in its simplicity--that the ending of one phrase defines, at the same time, the beginning of the next, and _vice versa_.