(bBordeaux, 13 Jan 1906; d Tarn, 26 Feb 1977). French composer and organist. He studied in Paris with Nat (piano), Koechlin (harmony) and Gédalge (composition), and came to notice when his Ouverture d’orchestre was given at the Champs Elysées in 1923. The conductor was Désormière, who in the same year joined Jacob in the Ecole d’Arcueil, a group formed around Satie. In 1929 Jacob converted to Catholicism and took holy orders. As a Benedictine novice at En-Calcat (Tarn) he made an intensive study of Gregorian chant and learnt the organ under Cabié and Duruflé; he took the name Clément. His later career was interrupted only by short periods as a soldier (1939–40) and an army chaplain (1944–5). Jacob’s music of the 1920s has a melodic richness and a spontaneity that caught the spirit of the time. The style, derived from Bizet, Gounod, Mendelssohn, Poulenc and Milhaud, was intended to delight. One result of Jacob’s conversion was a deepening of outlook. Simple harmonies gave place to a greater use of dissonance, and to modal shifts influenced by plainsong; above all, there was a move to more weighty subjects.