To the first class of instrumental compositions belong the toccatos, preludes, fugues and all works for the clavier written in fugal style. It should here be observed that the modern clavier, or pianoforte, had just been invented in Bach's time and was still in its crudest form. Bach did not intend his clavier compositions for this instrument, but for the clavichord and clavicembalo, which are of a different quality of tone and much inferior in volume to the hammer clavier at present in use. When this fact is taken into account, no false impressions need prevail concerning the effect of those earlier clavier pieces, which were so much in the style of organ music. We find among them many works of marked originality and beauty, such as the three magnificent toccatas in E minor, C minor and F major, written probably in the Weimar period and offering, even in our own day, the most grateful task which can be undertaken by an earnest and painstaking pianist. Bach's chamber music compositions, however, reached their highest point of perfection in Cöthen, as has been already stated. Here he created in 1723 that collection of artistic and soulful melodies, in the form of two and three-part clavier pieces, which received the name of "Inventionen und Sinfonien "; here also in 1722 he finished the first part of the "Wohltemperirte Clavier." This world-renowned work contains twenty-four preludes and fugues in all the major and minor keys of the twelve chromatic scales. Its title is due to the fact that the method of tuning an instrument in such a way as to secure purity of tone in nearly every key was first discovered in Bach's time. Until then, in the case of the clavier, the clavichord, etc., such keys as had either very few sharps or flats in the signature or none at all, had been tuned as correctly as possible and the remainder with proportionate inexactness. To distribute these unavoidable inaccuracies among the twelve keys of the instrument in such a way that, while no one of them attained perfect purity of interval, the deviations therefrom were too slight to offend the ear, was the task of the so-called "equal temperament." Bach's fame as an unsurpassed composer of fugues is founded especially upon the "Wohltemperirte Clavier," the contents of which were not composed at one time, but by degrees, many pieces dating from an early period of the artist's activity. The second part of the "Wohltemperirte Clavier" was completed in 1742. In this collection, the three-part fugue predominates and throughout the whole work there breathes that freedom and repose which are characteristic of the highest order of genius only. The first part is still more artistic, and Bach's command over the technicalities of the fugal style appears in it more plainly. Both parts have this in common, that they contain nothing but musical character-pieces of the first rank. The "Chromatische Fantasie und Fugue" may also have