Organist, Pianist, Composer. Reputedly the greatest French organist of his generation, and one of the founders of the French piano school. Séjan spent his whole life in his birthplace of Paris, initially studying organ with his uncle Nicolas-Gilles Forqueray, and composition with Louis Charles Bordier. His 1764 debut at the Concert Spirituel brought him instant fame as a virtuoso, revealing his genius at improvisation and a forward-looking keyboard technique. In 1772 he was named one of the four organists of Notre Dame Cathedral and went on to hold similar posts in other important Paris churches, including The Cordeliers (1773 to 1776), St. Severin (from 1782), St. Sulpice (from 1783), and the Royal Chapel (1789 to 1791). The French Revolution left Séjan unemployed by 1793, and while a stubborn royalist he adapted to the new regime enough to become first professor of organ at the new Paris Conservatory (1795 to 1802). Under Napoleon he was restored to most of his former church positions in addition to being named organist of The Invalides (1806); with the restoration of the Bourbon Monarchy (1814) he resumed his duties at the Royal Chapel. Louis XVIII personally awarded him the Legion of Honor in 1814. In his old age Séjan grew increasingly eccentric. He continued to dress in Louis XVI-era garb and insisted on being carried to his favorite organ at St. Sulpice even when he was too frail to play any longer. His original epitaph at Vaugirard Cemetery boasted of his connections with the French Kings; when that burial ground fell into disuse he was reinterred at Montmartre Cemetery. Although there are numerous written accounts of Séjan's primacy as an organist, his abilities are difficult to assess because he left almost no music for that instrument. Curiously, the only compositions published in his lifetime were two sets for piano: the "Six Sonatas, Op. 1" (1782) and the 13 pieces that comprise the "Recueil de pièces pour le clavecin ou le piano forte, Op. 2" (1783). These were among the earliest works written in France specifically for piano instead of the harpsichord, making Séjan a pioneer in the genre. After his death his widow extracted six organ pieces from his manuscripts, three fugues and three Noels. Colleagues attributed ballet music, violin sonatas and many other keyboard works to him, but none of it has come down to us.