Kandinsky was extremely influential, not only as one of the pioneers of abstract art, but equally as a theoretician, teacher and organiser. He and Marc led the Blaue Reiter project in Munich. In Moscow, as a post-revolutionary arts supremo, he worked with Rodchenko, Stepanova, Gabo, Pevsner, Popova, Malevich and Tatlin before an ideological split (Goncharova and Larionov kept on writing). Invited by Gropius to a post at the Bauhaus (with Klee a next-door neighbour), he invited his old friend Schoenberg to lead a music department there, though perceived anti-semitism halted the idea. Duchamp pointed him to a home in France.
Mies was one of the seminal modernist architects; his buildings possess superb proportion and an influential stripped-down aesthetic (echoed in his pithy aphorisms). His first job was with Paul; he then met Gropius, and probably Corbusier, as fellow-apprentices under Behrens. Lissitzky was a close friend and collaborator on the progressive design-journal ‘G’, along with Richter and Schwitters. Gropius, Kandinsky and Albers were Bauhaus colleagues. Aalto, Siskind and Callahan were friends, van Doesburg warmly so. An afternoon with Wright became four days. In the U.S., Johnson was a great supporter, and Beckmann, Gabo and Pevsner expatriate drinking companions.
Busoni’s stature as an influential composer and musical visionary is increasingly recognised. As a child prodigy he met Brahms and Liszt, and as a student, Mahler, Delius, Grieg and Tchaikovsky. He knew Boccioni well, and met his lifelong friend Sibelius through his teaching post in Helsinki. Among his many other pupils were Grainger, Weill, Wolpe, Krenek, Luening, and most significantly Varèse. He supported Bartók, corresponded with Schoenberg, and was helped by Rilke. In WW1 Zürich he knew Joyce, Zweig, Werfel and Bloch, and was regularly spotted out walking with his big dog Giotto by the young Elias Canetti.
Metzinger and Gleizes wrote the first theoretical study of cubism, having trialled their ideas through the Sunday discussion-group at Puteaux, run by Duchamp and his brothers. Picabia, Léger, Gris and Delaunay were also regular attenders. Gleizes, Metzinger, Delaunay and Léger got their work shown together at the Salon des Indépendants — in effect, the first cubist show. Cocteau asked Gleizes, in charge of troop-entertainment during WW1, to design Shakespearian sets. Picabia and Laurencin were fellow-exiles in Barcelona, and Duchamp and Picabia close friends when they and Gleizes moved on to New York.