The reputation which Domenichino had justly acquired at Rome had excited the jealousy of some of his cotemporaries, and the applause bestowed upon his Communion of St. Jerome, only served to increase it. The Cav. Lanfranco in particular, one of his most inveterate enemies, asserted that the Communion of St. Jerome was little more than a copy of the same subject by Agostino Caracci, at the Certosa at Bologna, and he employed Perrier, one of his pupils, to make an etching from the picture by Agostino. But this stratagem, instead of confirming the plagiarism, discovered the calumny, as it proved that there was no more resemblance between the two works than must necessarily result in two artists treating the same subject, and that every essential part, and all that was admired was entirely his own. If it had been possible for modest merit to have repelled the shafts of slander, the work which he executed immediately afterwards in the church of S. Lodovico, representing the life of St. Cecilia, would have silenced the attacks of envy and malevolence; but they only tended to increase the alarm of his competitors, and excite them to redoubled injustice and malignity. Disgusted with these continued cabals, Domenichino quitted Rome, and returned to Bologna, where he resided several years in the quiet practice of his profession, and executed some of his most admired works, particularly the Martyrdom of St. Agnes for the church of that Saint, and the Madonna del Rosario, both of which were engraved by Gerard Audran, and taken to Paris and placed in the Louvre by order of Napoleon. The fame of Domenichino was now so well established that intrigue and malice could not suppress it, and Pope Gregory XV. invited him back to Rome, and appointed him principal painter, and architect to the pontifical palace.