Titelouze was a friend of Marin Mersenne, an important French music theorist, mathematician, philosopher and theologian. Seven letters survive from their correspondence, from 1622–1633. Titelouze gave Mersenne advice on "L'Harmonie Universelle", published from 1634 to 1637. Although the strict polyphonic style of Titelouze's music soon disappeared from French organ music, his influence was still felt for some time after his death; for instance, the Parisian composer and organist Nicolas Gigault included a fugue "à la maniere de Titelouze" (literally "in Titelouze's style") in his 1685 "Livre de musique pour l'orgue". Some three hundred years later, the composer inspired one of Marcel Dupré's organ works, "Le Tombeau de Titelouze", op. 38 (1942).