From childhood this son, Christian Frederick Müller, had been devoted to his father's art. His first attempts were successful enough to warrant his early admittance to the school of engraving recently founded at Stuttgart by Duke Charles of Wurtemberg. We have seen that during the second half of the eighteenth century many German engravers came to Paris for training, and that many remained there. Expelled from France, their adopted country, by the Revolution, they returned to Germany, and the institution of a school of engraving in Stuttgart was one result of their expulsion. But by 1802 many of the fugitives were already back in Paris, and the studios, closed for ten years, once more opened their doors to numerous pupils. Frederick Müller, then barely twenty, followed his father's example, and in his turn went to perfect himself under French masters. Commended to the good offices of Wille, then past eighty, who felt it an honour to have taught Johann Godard Müller, and introduced by him, the young man was soon in relation with Bervic, Tardieu, and Desnoyers; and without constituting himself a thorough-going imitator of these fine craftsmen, he yet borrowed enough from them to be considered, if not their rival, at least one of their most faithful disciples. The plates he engraved for the "Musée Français," published by Laurent and Robillard,[50] show laudable submission to the principles of the masters and an already sound experience of art; but it is in the "Madonna di San Sisto," in which he seems to have arrived at maturity, that his talent may be fully measured. Before undertaking this plate, the young engraver went to Italy to study other work by the "Divine Painter," and to prepare himself for the interpretation of the picture in the Dresden Gallery by drawing from the Vatican frescoes. On his return to Germany, he at once applied himself to the task, and pursued it with such ardour that, towards the end of 1815, that is in three years, he had brought it to an end. The "Madonna di San Sisto" deserves to rank with the finest line engravings of the beginning of the century. It has long been popular; but renown came too slowly for the engraver, and unhappily he lacked the patience to await its coming.