But it was the classical masters of the sonata period who dealt with the matter effectually. They based their scheme of organization on the recognition of a complete classification of the harmonic contents of any key; which implied a recognition of the actual degrees of importance and of the functions of each individual chord. This scheme also required as its most essential guaranty a very strict recognition and observance of each key that became a factor in the form; and also the apprehension of chords as chords. But when the true polyphonic spirit invaded the sacred precincts of the sonata type, and means were supplied to slip from diatonic chord to chromatic chord, and even for a composer to lead the pleasingly bewildered hearer into some unimaginable remote key and back, it began to dawn on people that the achievement of even such an admirable principle of organization as the sonata form had not landed musicians in their final haven, but that in reality the sonata period was merely one of transition--a kind of interim, like that of the aria form in opera, when men forebore for a time to address themselves to expression, and projected their minds to the solution of the essential problems of organization. The wonderful success which the sonata composers achieved in their devoted self-denial led to the unfortunate misconception that musical art was a thing which stood by itself and was self-sufficient and had no reference in its highest manifestations to anything outside itself. Two things corrected this strange aberration. One was that a race of composers sprang up who filled up the easily managed forms of the sonata type with correct and orthodox passages and deluged the world with utterly barren, empty, artificial and intolerably conventional rigmarole. This, indeed, the world could not put up with, and it turned with not unnatural eagerness to welcome the party who advocated program music. These aspiring people were quite on the right tack, but the resources of art were not as yet built up sufficiently for their purposes, and therefore a great part of their trivial and conventional imitations of scenes and impressions merely made them ridiculous. The necessary revolution came out of the heart of the old régime. The greatest masters of the sonata types of art had always been impelled to infuse their works of the sonata order with human meaning and to suggest a condition of feeling--mournful, cheerful, merry, mischievous, and the like; and Beethoven, the greatest of them all by far, after showing frequent signs of breaking away even as early as the slow movement of his Sonata in D, opus 10, No. 3, finally in his latest sonatas, quartets and symphonies produced some of the most wonderful human documents ever achieved by man, in which he expressed the workings of his own innermost feelings, the portrayal of his aspirations, his perplexities in face of the problems of life, his