He returned to Paris early in 1836, and at once sought for a hearing at the Opéra Comique, the first ambition of a young French composer. He did not have long to wait, for in August, 1837, his one-act opera, “La Double Echelle,” was performed, and so favorably received that he obtained a firm foothold at the opera house and produced there “Le Perruquier de la Régence,” three acts (1838); “Le Panier Fleuri,” one act (1839). In the meanwhile, encouraged by his success, he aspired to the Académie, and in 1839 produced there, in collaboration with Benoist, La “Gipsy,” a ballet in two acts. He also composed for the same establishment “Le Comte de Carmagnola” (1841); “Le Guerillero” (1842); and “Betty,” a ballet in two acts (1846). None of these was successful. At that time Auber, Halévy, Meyerbeer and Donizetti were composing for the Académie, and it was not easy for a young artist to hold his own against them. Thomas had not neglected the Opéra Comique, for which he wrote “Carline” (1840); “Angélique et Médor” (1843); “Mina” (1843), all of which failed to make any favorable impression on the public. Discouraged by the lack of success that attended his efforts, he ceased to write for the lyric stage, and for five years remained silent. When he was heard again it was in “Le Caïd,” a three-act comic opera, which was produced in 1849, and achieved a brilliant success, making a tour of Europe. It was followed in 1850 by “Le Songe d’une nuit d’été,” in three acts. This opera was no less fortunate in the reception accorded it, and at once gave Thomas a foremost place among the young French composers of the day. Then came “Raymond,” three acts (1851); “La Tonelli” (1853); “La Cour de Célimène” (1855); “Psyché” (1857); “Le Carnaval de Venise” (1857); “Le Roman d’Elvire.” Some of these obtained slight temporary success, but not one of them won the popularity that attended “Le Caïd” and “Le Songe.” Again Thomas retired from view, and this time it was six years before he produced another opera. In 1851 he became a member of the Institute, and in 1852, Professor of Composition in the Conservatoire. Up to this time Thomas had distinguished himself as a fluent and refined melodist, and by his piquant orchestration; he was also noted as a master of musical comedy. Nevertheless he had not yet been able to win for himself a rank equal to that of Auber, and in French comic opera, “Le Maçon,” “Fra Diavolo,” “Le Domino Noir,” and “Les Diamants de la Couronne,” which had been composed before Thomas went into his second seclusion, still surpassed all that the latter had produced, and survive to this day, while, with the exception of “Le Caïd,” none of Thomas’s operas antecedent to 1850 are ever performed.