are in a position to express themselves fully, and the dance alone preserves the continuity of the whole. The combination of three dances simultaneously in varied rhythm and expression, offered to Mozart a task in counterpoint which he has accomplished with so much ease and certainty, that the untechnical listener scarcely believes in its difficulty. The arithmetical calculation that three bars in 2-4 are equal to two bars in 3-4, and one bar 3-8 represents a crotchet in a triplet, is easily made, and the system presents no difficulty. But the problem really consists in concealing the system beneath the melody and rhythm, and in causing the necessary coincidence of the phrasing to appear a natural and unstudied one, dependent on the individual character of each dance. One dance follows another as a matter of course. The minuet begins--the same which has been heard before. At the repetition of the second part, the second orchestra prepares to strike up, the open strings are struck in fifths, touched _pizzicato_, and little shakes tried, the violoncello joins in in the same way--and all falls naturally into the minuet, as it pursues its even course.[181] At last a gay country dance (2-4) strikes up, as different in melody and rhythm from the minuet as can be, although it is of course constructed on the same fundamental bass. At the second part, the third orchestra proceeds to tune up as the second had done before, and falls in with a fresh and merry waltz (3-8).[182] Before the minuet recommences, Zerlina's cry for help is heard, both dances and music break off suddenly, and the orchestra, which has hitherto been silent, strikes in with full force.[183] Zerlina's cry for help brings about a complete change of {DON GIOVANNI.} (210)