In fact the development of the instrument itself affected the development of the technics of playing, and these affected the evolution of piano music. Then the music itself reacted on the technic, and this made new demands of the instrument makers. We have seen that when the early pianists set about the formulation of rules for playing their instruments they made poor work of it. Their rules were arbitrary and were not evolved from a study of the natural action of the hand. Smooth running of scale passages with such rules as those of Lorenzo Penna could be accomplished only at a very moderate pace. The old polyphonic compositions for the clavichord and harpsichord demanded of the player a technic which would enable him to bring out clearly the three or four voice parts. The new style, which borrowed so much from vocal music, naturally sought for a smooth, flowing, even performance, in which the instrument should, as nearly as possible, sing like a solo voice with accompaniment. Emmanuel Bach, who wrote an important book on clavichord playing, proclaimed his belief that the singing style was the only true one for the instrument. These early musicians had, indeed, arrived at the heart of the matter, for the highest achievement of piano technic to-day is the preservation of a pure singing tone throughout the intricacies of modern music. The discovery of the value of the thumb revolutionized clavichord and harpsichord playing. George Frederick Handel (1685-1759) and François Couperin (1668-1733) both made free use of the thumb, but it was Johann Sebastian Bach (1685-1750) who systematized its employment. He decided that the old position of the hand with the back flat and the fingers stretched to their full extent was unnatural. He saw that the whole strength of the fingers could not be brought to bear while they were in this position, and that the thumb could not be placed upon the keyboard at all. When he attempted to use his thumb, he had to raise the back of his hand and bend his fingers, and this he saw at once placed the whole hand in a position of command over the keyboard which it had never before possessed. He therefore rearranged the fingering of all the scales, introducing the system which still continues in use. Bach himself discovered that with his new system of fingering he could play polyphonic or monophonic music with equal ease, and hence we find that his compositions abound in both kinds of writing. He himself, being a church composer, naturally clung to the ecclesiastic style, and in his great organ and piano fugues transferred the whole contrapuntal science of the fifteenth and sixteenth centuries to instrumental music. But we shall see that better when we come to a consideration of the music apart from the technic and the style.