That event was withdrawal from the musical world and the initiation of a long course of the severest study. When he was a little over twenty-one, Brahms imposed upon himself this arduous training, and commanded himself to forego for a while the eloquent but ill-controlled expression hitherto his, in order to acquire a broader, firmer, purer, and stronger style. For four or five years, to borrow Stevenson's expression, he «played the sedulous ape» to Bach and Beethoven, and in a minor degree to Haydn and Mozart. The complex harmonies of his first period gave place to simple, strong successions of triads; for an emotional and often vague type of melody he substituted clearly crystallized, fluent, and gracious phrases, frequently devoid of any particular expression; the whimsical rhythms of the piano sonatas were followed by the square-cut sections of the Serenade, opus 11. Of course the immediate effect of all this was a great sacrifice of what is called originality; had Brahms not had complete faith in the vitality of his genius he could not have surrendered so much of immediate attainment for the sake of an ultimately greater mastery. It is a profound lesson in the ethics of art that a man who could write the fourth of the Ballades, opus 10, should have been willing to follow it up with this Serenade, opus 11. Yet Brahms knew what he was about, and his first large work, the Piano Concerto, opus 15, shows his individuality of expression entirely regained, and now with immensely increased power and resource. Nothing could exhibit better than this dissatisfaction with his early work and withdrawal from the world for study, that intellectual breadth which we have noted as characteristic of Brahms. He was not a man who could be content with a narrow personal expression. No subjective heaven could satisfy him. His wide human sympathy and his passion for artistic perfection alike, compelled him to study unremittingly, to widen his ideals as his powers increased. No fate could seem to him so horrible as that «setting» of the mind which is the æsthetic analogue of selfishness. Originality, which so often degenerates into idiosyncrasy, was much less an object to him than universality, which is after all the best means of being serviceably original. Dr. Deiters, in his reminiscences, after describing this period of study, continues: «Henceforth we find him striving after moderation, endeavoring to place himself more in touch with the public, and to conquer all subjectiveness. To arrive at perspicuity and precision of invention, clear design and form, careful elaboration and accurate balancing of effect, now became with him essential and established principles.»