Moscheles wrote to his wife that Chopin's "_ad libitum_ playing, which, with the interpreters of his music degenerates into offences against correct time, is, in his own case, merely a pleasing originality of style." He compares him to "a singer who, little concerned with the accompaniment, follows entirely his feelings." Karasovski says that Chopin "played the bass in quiet, regular time, while the right hand moved about with perfect freedom, now following the left hand, now ... going its own independent way. 'The left hand,' said Chopin, 'must be like an orchestral conductor; not for a moment must it be uncertain and vacillating.'" Thus his playing, free from the fetters of _tempo_, acquired a unique charm; thanks to this _rubato_, his melody was "like a vessel rocked upon the waves of the sea." The world suffered a great loss when a band of ignorant soldiers found the bundles of letters which Chopin had written from Paris to his parents, and used them to feed the fire which cooked their supper. But it lost a still greater treasure when Chopin tore up the manuscript of his pianoforte method, which he began to write in the last years of his life, but never finished. In it he would no doubt have given many valuable hints regarding the correct use of the _rubato_. In the absence of other authentic hints beyond the one just quoted, Liszt must be depended upon as the best authority on the subject; for it is well known that Liszt could imitate Chopin so nicely that his most intimate friends were once deceived in a dark room, imagining that Chopin was playing when Liszt was at the piano. "Chopin," Liszt writes, "was the first who introduced into his compositions that peculiarity which gave such a unique color to his impetuosity, and which he called _tempo rubato_:--an irregularly interrupted movement, subtile, broken, and languishing, at the same time flickering like a flame in the wind, undulating, like the surface of a wheat-field, like the tree-tops moved by a breeze." All his compositions must be played in this peculiarly accented, spasmodic, insinuating style, a style which he succeeded in imparting to his pupils, but which can hardly be taught without example. As with the pedal, so with the _rubato_, Chopin often neglected to mark its use in later years, taking it for granted that those who understood his works would know where to apply it. Perhaps the importance of the _rubato_ in Chopin cannot be more readily realized than by his concession that he could never play a Viennese waltz properly, and by the fact that sometimes, when he was in a jocular mood, he would play one of his mazurkas in strict, metronomic time, to the great amusement of those who had heard him play them properly.