Copland, of these composers, undoubtedly was the most successful. However, he dropped the experiment after two or three works of this type, which can be counted among his best, in order to write, over a period of several years, music of a different kind, characterized by certain lean and harsh dissonances, angular, sharp, and at moments melancholy and which no longer had a connection with jazz. There is much more to say about this composer, whose music has passed also through other phases. It may be asked, however, why he decided to abandon the idiom chosen at the outset of his career, one based on jazz. Probably he saw the limitations of nationalist ideas as such and, like the European composers mentioned, came to the realization that by its very nature jazz is limited not only as material, but emotionally as well. Jazz may be considered a _genre_ or a type, yet one discovers quickly that, passing beyond certain formulas, certain stereotyped emotive gestures, one enters the sphere of other music, and the concept of jazz no longer seems sensible. The character of jazz is inseparably bound to certain harmonic and rhythmic formulas--not only to that of syncopation but, if incessant syncopation is to make its full effect, to the squarest kind of phrase structure, and to a harmony based on most primitive tonal scheme. While immobility of these bases makes a play of rhythmic detail and of melodic figuration possible, this always is a question of lively detail rather than of extended organic development. The result is exactly what might have been expected: for the last twenty years, leaving aside occasional instances where jazz was frankly and bodily “taken over” for special purposes, it has ceased to exert a strong influence on contemporary music. On the contrary, it has borrowed incessantly from “serious” music, generally after a certain interval of time. Though different from Copland, the equally gifted George Gershwin travelled in the opposite direction; from popular music he came to the extended forms of “serious” music. He remained a composer of “popular” and “light” music, nevertheless, for they were native to him. If his jazz is always successful and unproblematical even in his large works, like the _Rhapsody in Blue_ and the opera _Porgy and Bess_, it is because in its original and popular sense jazz is his natural idiom, and Gershwin never felt the need for overstepping its limits, musical or emotive. True, he wanted to write works of large design, but herein he never succeeded. He never understood the problem and the requirements of extended form, and remained, so to speak, innocent of them. But since his music was frankly popular in character and conception, it developed without constraint within the limits of jazz; and since he was enormously gifted, it could achieve a quality transcending the limits of jazz convention.