Sor and Francisco Tárrega. Segovia's influence enlarged the repertoire, mainly as a commissioner or dedicatee of new works, as a transcriber, and as a composer with such works as his Estudio sin luz. Segovia's main musical aesthetic preferences were music of the early 20th century (and turn of the century) especially in the Spanish romantic-modern and nationalist style. That is perhaps best typified by Segovia's own work Estudio sin Luz. Many works of that and similar styles were written especially for him and formed part of his core repertoire: particularly the guitar works of Federico Moreno Torroba (1891–1982), such as the Sonatina, which was first performed by Segovia in Paris in 1925. Segovia was selective and performed only works with which he identified personally. He was known to reject atonal works or those that he considered too radical even if they were dedicated to him; he rejected Frank Martin's Quatre pièces brèves, Darius Milhaud's Segoviana, etc. Even though rejected by Segovia, all of those works are today published and available. Teaching Segovia viewed teaching as vital to his mission of propagating the guitar and gave master classes throughout his career. His most famous master classes took place at Música en Compostela, in the Spanish city of Santiago de Compostela. Segovia also taught at the Accademia Musicale Chigiana in Siena for numerous years, where he was aided by Alirio Díaz. Later it was Oscar Ghiglia who continued the Siena class. His teaching style is a source of controversy among some of his former students, who considered it to be dogmatically authoritarian. One of Segovia's most celebrated former students of the classical guitar, John Williams, has said that Segovia bullied students into playing only his style and stifled the development of their own styles. Williams has also said that Segovia was dismissive of music that did not have what Segovia considered the correct classical origins, such as South American music with popular roots. He was also critical of Williams' work with the group Sky for the same reasons. Legacy Segovia can be considered a catalytic figure in granting respectability to the guitar as a serious concert instrument capable of evocativeness and depth of interpretation. Federico Moreno Torroba said, "The musical interpreter who fascinates me the most is Andrés Segovia." He can be credited to have dignified the classical guitar as a legitimate concert instrument before the discerning music public, which had hitherto