For an illustration, see Beethoven's sonata, op.

14, No.

2, first movement: The Principal theme is a Two-Part Song-form; Part I, a period, from measures 1 to 8; Part II begins in measure 9, and has every appearance of becoming also a period; its Antecedent phrase closes in measure 12, its Consequent begins in measure 13--but its end, _as Second Part_, in the usual definite manner, cannot be indicated; the key is quietly changed from G to D, and then to A, in obedience to the call of the Subordinate theme (beginning in measure 26), into which these last 10 or 12 measures have evidently been a Transition.

The Second Part of the Principal theme therefore includes the transition; but where the Second Part (as such) ends, and the transition (as such) begins, it is impossible to point out accurately.

The definition of this Principal theme is, "Two-Part form with dissolved Second Part," or, still better, "_with transitional Second Part_." * * * * * * In our illustration of the sonata-allegro form it is necessary, on account of limited space, to select a very concise example, of unusual brevity,--Beethoven, sonata, op.