Einstein, Bohr, Bergson and de Broglie were personal friends and correspondents. Louÿs introduced both Mallarmé and Gide to him: he became Mallarmé’s protégé, regularly attending his literary evenings. He met Curie in Spain, Rilke in Switzerland, and Conrad when inaugurating a plaque marking Verlaine’s London lodgings. Degas introduced him to his future wife, Breton asked him to be his best man, Honegger collaborated on an opera-ballet, and Tailleferre on a cantata. Stravinsky felt he thought too much about thought. Later in life, Gide persuaded him to publish the poetry he’d written years earlier.