In addition, Kuhnau wrote thirteen sonatas. The "Frische Clavier Fruechte," or "Sieben Suonaten von guter Invention u. Manier auf dem Clavier zu spielen," were published in 1696, and later editions in 1710 and 1724. In a quaint preface the composer tells us that in naming his "Fresh Fruits" "sonatas," he kept in mind all kinds of _inventiones_ and changes (Veraenderungen) by which so-called sonatas are superior to mere partitas. Already a century before this preface was written, Praetorius had distinguished between two classes of instrumental music: the one, grave; the other, gay. The composer has also a word to say about the graces or ornaments, the "sugar which sweetens the fruits." In modern reprints of Kuhnau the sugar is sometimes forgotten.[43] These "Frische Fruechte" were followed by six "Bible" Sonatas in 1700. The former, both as regards form and contents, are remarkable. Kuhnau was a man of deeper thought and loftier conception than Emanuel Bach, but he was fettered by fugal forms,[44] and was fighting against them much in the same spirit in which Beethoven, a century later, fought against sonata-form, in the most general sense of that term. Beethoven was not only the more gifted, but he profited by the experiments of his predecessors, and he enjoyed the advantage of a vastly improved technique; Haydn, Mozart, Clementi, and others were the stepping-stones by which he rose to higher things. Kuhnau's attempts at sonata writing were bold, often rugged; and his experiments in programme-music, extraordinary. The latter were soon forgotten, while the clever, clear-formed sonatas of Emanuel Bach served as a gratification to the age in which he lived, and as guides to the composers who followed him. The "Frische Fruechte," standing between Corelli and Emanuel Bach, are of interest. The fugal element is still strong; and we find, not so much the smooth style of Corelli as the vigorous style of Froberger and other composers of North Germany. In character of subject-matter and in form there is decided advance as compared with the B flat Sonata. Kuhnau still seems rather limited in figures, and therefore repeats himself;[45] then again his movements do not always show gradation of interest. Their order and number are, indeed, perplexing, and not always satisfactory. The 2nd Sonata, in D, for instance, commences with a fine Allegro, followed first by a short Adagio, commencing in the relative minor, and intermixed with short presto passages, and then by a lively movement in six-eight time. These three would form an admirable sonata, yet the composer does not end here. There is still another short Adagio, and a concluding movement; and in spite of some fine passages, these appendages form a decided anti-climax. Similar instances are to be found in the other sonatas.