expect, is followed by the chord of the 6th of the key, or sub-mediant, thus—
But in point of fact this gives but a very small notion of what an interrupted cadence really is. For it can only be distinguished from an imperfect cadence with certainty by reference to the context. The latter is a definite stop occurring in the natural course of the music, and marking a period, though not in such a way as to enable the passage which it ends to be taken as complete in itself. But the former is an abrupt and irregular interruption of the natural flow of the music towards its anticipated termination in a perfect cadence, postponing that termination for a time or altogether avoiding it. Thus at the end of the first movement of the Sonata in C, op. 53, Beethoven keeps on postponing the perfect cadence in this manner—
In his later works an entire evasion of the cadence is frequent, as in the first movement of the Sonata in E, op. 109—
It is a common practice with writers of treatises on harmony to give a series of chords preparatory to the two final ones which are given above as the perfect cadence. This makes it look as though the treatises were meant to teach people to make music at so much a yard; for a man who really has something to say in music which he feels naturally is only hampered and worried with every extra direction of the kind, which tells him to put in so much that cannot possibly mean anything because it is everybody's property. A real musician only requires directions and general principles, which are capable of considerable expansion according to the power of his genius. The rule seems simply to be that, relative to the degree in which the cadence is final, the passage which immediately precedes it must mark the key in which it is made. The sense of the key in which any movement is written is of extreme importance for the comprehension of the music, especially in instrumental music, and such as depends much upon its form of construction. Hence a cadence of any finality must mark the key strongly. Subordinate cadences, such as occur in the course of the movement, especially apart from the broader divisions of the movement, need not be so marked; but if the final cadence of the whole movement, or that of an important subdivision of a movement, is simply a couple of chords or so immediately succeeding a passage in a foreign key, the sense of whereabouts is lost, and an entirely unsatisfactory effect produced by the indecisiveness of the conclusion.
The tendency of modern music has been to avoid full cadences in the course of a piece of music, and when they become necessary to vary them as much as possible. The former, because frequent cadences make a movement into a fragmentary series of continually recommencing passages, coming each time to a full stop and beginning again; the latter, because the mind has become so habituated to the form of the ordinary perfect cadence that in a movement of highly emotional character it comes rather like a platitude. Besides, though form is a great and often the principal element of beauty in a movement, to make it too obvious by the marked nature of the cadences destroys the interest and freshness of the work. Mozart marked the divisions of his movements very strongly, but in his day the forms of instrumental music were not by any means so familiar as they are now, and their being strongly marked was necessary for their due comprehension. Besides, in Mozart's day people had much more time to sit down and rest between one action and another than they seem to have now, and perfect cadences are exactly like sitting down and resting when one tune is over so as to be fresh for the next when it makes its appearance. And the analogy goes even further, for the movement in which one sits down least often and least completely is that which is most like one great action with a single principle at its basis rather than a series of somewhat disconnected motions, which are chiefly recommended by their mutual contrasts and relative proportions.With regard to the position of the chords in the bar, the commonest position is that in which the final chord is on the first beat of the bar, or