During the last generation an advance in material complexity is obvious, even though the complexity may often enough be one of accidentals rather than essentials. An orchestral score of Wagner is relatively simple in comparison with one of Delius or Ravel or Scriabin or Stravinsky or Schoenberg; and the demands on performers' technique and also on their intelligence have steadily increased to heights altogether unknown before. The composer has at his present disposal a vastly enlarged medium; the possibilities of sound have developed incalculably more than those of paint or stone or marble. Pheidias could, we may imagine, have appreciated Rodin across a gulf of over two thousand years; but it is difficult to see the points of contact, after little over three hundred years, between Palestrina and any twentieth-century work that would claim to be 'in the movement'. And it is not only in complexity that we have advanced. We have extended the limits of musical style. We have adopted in sober earnest methods forecasted at rare intervals in the past by adventurous explorers, and employ musical notes not as elements in any harmonic scheme but purely as points of colour, exactly as if the definite notes were mere clangs of indefinite instruments like cymbals or triangles. Wordless vocal tone, moreover, of several different types, is pressed into the same service. Varied tonal and harmonic colour, and structural freedom: those are the two battle-cries of the young generation. Little by little the old tonalities, based as they were on fixed centres, are slipping away; all the notes of the chromatic scale are acquiring even status; the principles of structure are newborn with every new work. And advance of this kind has been extraordinarily accelerated during the last twenty years. At no time in musical history have there been such express-speed modifications of manner as those which divide, let us say, the latest piano pieces of Brahms (1893) and the latest of Scriabin (1914). It is possible, indeed, that our standard system of keyboard tuning may require modification in the not very distant future. Once again, as three hundred years ago, music seems to be in the throes of a new birth. On the former occasion, the process of convalescence lasted rather more than a century, from Monteverde through Carissimi and Schuetz and Purcell to Bach; and it may perhaps take as long now.