his colleague Zoltán Kodály as another Hungarian adherent of neoclassicism. A German strain of neoclassicism was developed by Paul Hindemith, who produced chamber music, orchestral works, and operas in a heavily contrapuntal, chromatically inflected style, best exemplified by Mathis der Maler. Roman Vlad contrasts the "classicism" of Stravinsky, which consists in the external forms and patterns of his works, with the "classicality" of Busoni, which represents an internal disposition and attitude of the artist towards works. Busoni wrote in a letter to Paul Bekker, "By 'Young Classicalism' I mean the mastery, the sifting and the turning to account of all the gains of previous experiments and their inclusion in strong and beautiful forms". Neoclassicism found a welcome audience in Europe and America, as the school of Nadia Boulanger promulgated ideas about music based on her understanding of Stravinsky's music. Boulanger taught and influenced many notable composers, including Grażyna Bacewicz, Lennox Berkeley, Elliott Carter, Francis Chagrin, Aaron Copland, David Diamond, Irving Fine, Harold Shapero, Jean Françaix, Roy Harris, Igor Markevitch, Darius Milhaud, Astor Piazzolla, Walter Piston, Ned Rorem, and Virgil Thomson. In Spain, Manuel de Falla's neoclassical Concerto for Harpsichord, Flute, Oboe, Clarinet, Violin, and Cello of 1926 was perceived as an expression of "universalism" (universalismo), broadly linked to an international, modernist aesthetic. In the first movement of the concerto, Falla quotes fragments of the 15th-century villancico "De los álamos, vengo madre". He had similarly incorporated quotations from 17th-century music when he first embraced neoclassicism in the puppet-theatre piece El retablo de maese Pedro (1919–23), an adaptation from Cervantes's Don Quixote. Later neoclassical compositions by Falla include the 1924 chamber cantata Psyché and incidental music for Pedro Calderón de la Barca's, El gran teatro del mundo, written in 1927. In the late 1920s and early 1930s, Roberto Gerhard composed in the neoclassical style, including his Concertino for Strings, the Wind Quintet, the cantata L'alta naixença del rei en Jaume, and the ballet Ariel. Other important Spanish neoclassical composers are found amongst the members of the Generación de la República (also known as the Generación del 27), including Julián Bautista, Fernando Remacha, Salvador Bacarisse, and Jesús Bal y Gay. A neoclassical aesthetic was promoted in Italy by Alfredo Casella, who had been educated in Paris and continued to live there until 1915, when he returned to Italy to teach and organize concerts, introducing modernist composers such as Stravinsky and Arnold Schoenberg to