Upon his return to Salzburg young Mozart became concert master at the archiepiscopal court, and partly under pressure of demands for occasional music, partly spurred on by a most extraordinary creative impulse, he turned out works of every description--ecclesiastical and secular; symphonies, sonatas, quartets, concertos, serenades, etc., etc. He had written no less than 288 compositions, according to the latest enumeration,[42] when, at the age of twenty-one, he was driven by the insufferable conditions of his servitude to take his departure from home and seek his fortune in the world. This event marked the period of his artistic adolescence. Accompanied by his mother he went over much of the ground covered during his journey as a prodigy, but where before there was universal acclaim he now met utter indifference, professional opposition and intrigue, and general lack of appreciation. However futile in a material sense, this broadening of his artistic horizon was of inestimable value to the ripening genius. While equally sensitive to impressions as before, he no longer merely imitated, but caught the essence of what he heard and welded it by the power of his own genius into a new and infinitely superior musical idiom. Now for the first time he rises to the heights, to the exalted beauty of expression which has given his works their lasting value. Already in the fullness of his technical power, equipped with a musicianship which enabled him to turn to account every hint, every suggestion, this virtuoso in creation no less than execution fairly drank in the gospel of classicism. Mannheim became a new world to him, but in his very exploration of it he left the indelible footprints of his own inspiration.