When the boys reached Paris, in 1822, Hector loyally tried to keep his promise to his father and threw himself into the studies which were so repugnant to him. He says he might have become a common-place physician after all, had he not one night gone to the opera. That night was a revelation; he became half frantic with excitement and enthusiasm. He went again and again. Learning that the Conservatoire library, with its wealth of scores, was open to the public, he began to study the scores of his adored Gluck. He read, re-read and copied long parts and scenes from these wonderful scores, even forgetting to eat, drink or sleep, in his wild enthusiasm. Of course, now, the career of doctor must be given up; there was no question of that. He wrote home that in spite of father, mother, relations and friends, a musician he would be and nothing else.
A short time after this the choir master of Saint Roch, suggested that Hector should write a mass for Innocents' Day, promising a chorus and orchestra, with ample rehearsals, also that the choir boys would copy the parts. He set to work with enthusiasm. But alas, after one trial of the completed work, which ended in confusion owing to the countless mistakes the boys had made in copying the score, he rewrote the whole composition. Fearing another fiasco from amateur copyists, the young composer wrote out all the parts himself. This took three months. With the help of a friend who advanced funds, the mass was performed at Saint Roch, and was well spoken of by the press.
The hostility of Hector's family to music as a profession, died down a bit, owing to the success of the mass, but started up with renewed vigor when the son and brother failed to pass the entrance examinations at the Conservatoire. His father wrote that if he persisted in staying on in Paris his allowance would be stopped. Lesueur, his teacher, promised to intercede and wrote an appealing letter, which really made matters worse instead of better. Then Hector went home himself, to plead his cause in person. He was coldly received by his family; his father at last consented to his return to Paris for a time, but his mother forbade it absolutely. In case he disobeyed her will, she would disown him and never again wished to see his face. So Hector at last set out again for Paris with no kind look or word from his mother, but reconciled for the time being with the rest of the family.