His system of tempering or tuning the clavichord, by reason of which he has often been granted a historical immortality, was the relatively simple one of dividing the octave into twelve equal intervals. Only the octave itself was strictly in tune, but the imperfections of the other intervals were so slight as to escape detection by the most practised ear. By paying the nominal toll of theoretical inaccuracy, Bach opened the roads of harmonic modulation on every hand. It must not be forgotten, however, that most of the pieces of Couperin or Scarlatti, not to mention many an outlandish chromatic _tour de force_ in the works of the early English composers, would have been intolerable on a harpsichord strictly in tune. Other men than Bach had their systems of temperament. We may take Bach’s only to be the simplest. Furthermore, that he created a new development of pianoforte technique by certain innovations in the manner of fingering passages, is open to question. It is well known that up to the beginning of the eighteenth century the use of the thumb on the keyboard was generally discountenanced. Bach himself had seen organists play who avoided using the thumb even in playing wide stretches. Scales were regularly played by the fingers, which, without the complement of the thumb, passed sideways over each other in a crawling motion which is said to have been inherited from the lutenists. Couperin advocated the use of the thumb in scales, but _over_, and not under, the fingers. Bach seems the first to have openly advised and practised passing the thumb under the fingers in the manner of today. Yet even he did not give up entirely the older method of gliding the fingers over each other in passages up and down the keyboard. His system passed on through the facile hands of his son Emanuel, the greatest teacher of the next generation; and if it is not the crest of the wave of new styles of playing which was to break over Europe and flood a new and special pianoforte literature, is at any rate a considerable part of its force. Yet it must be borne in mind that Scarlatti founded by his own peculiar gifts a tradition of playing the piano and composing for it, in which Clementi was to grow up; and that, influential as Emanuel Bach was, Clementi was the teacher of the great virtuosi who paved the way to Chopin, the composer for the piano _par excellence_. The foundation of all Bach’s music is the organ. Even in his works for violin alone, or in those for double chorus and instruments, the conjunct, contrapuntal style of organ music is unmistakable. His general technique was acquired by study of the organ works of his great predecessors, Frescobaldi, Sweelinck, Pachelbel, Buxtehude, Bohm, and others. He was first and always an organist. So it is not surprising to find by far the greater part of his harpsichord and clavichord music shaped to a polyphonic ideal; and, what is more, written in the close, smooth style which is primarily fitting to the organ.