Deleuze and Butor became friends as philosophy students at the Sorbonne; Tournier was another fellow-student, and in later years admired his writing. Wahl employed Butor as his secretary. His friends Barthes and Klossowski both lived with their aged mothers in neighbouring streets; at parties, Barthes sometimes played piano duets, and Butor sometimes sang. Barthes was also the first critic to identify the aims of his writing. Butor collaborated extensively with musicians and artists, the composer Pousseur and the artist Kolář among those who worked regularly with him.