Two centuries separate the lives of Johann Sebastian Bach and Eugène Ysaÿe, two centuries of differences and similarities. In the first half of the 18th century, J.S. Bach developed into a compositional genius with an enormous repertoire. In the beginning of the 20th century, Ysaÿe emerged as a world- famous violinist. He also composed, but less than his illustrious predecessor.As children, both received violin les- sons from their fathers, Bach in his birthplace Eisenach and Ysaÿe in his native Liege. Bach was equally drawn to the violin, the harpsichord and the organ. Ysaÿe was obsessed with the one instrument. Bach earned his living writing whatever music his employers required of him. From the time of his appointment as cantor at the Lutheran Thomaskirche in Leipzig in 1723, he wrote principally church music. Before that, he had been kapellmeisterat the court of Prince Leopold of Anhalt-Cöthen. As it was not custom- ary for sacred music to be heard at this Protestant court, Bach was expected to write secular music.
From 1717 to 1723, he composed violin concertos, The Well-Tempered Clavier, pieces for solo organ, harpsichord and cello, and sonatas and partitas for the violin. Most of his younger contemporaries, including his son Carl Philipp Emanuel, considered his music old-fashioned. In doing so, they appar- ently neglected The Well-Tempered Clavier, in which Bach experimented with keys, new sonorities and daring modulations from one key to another.
The new tuning system for keyboard instruments, called “equal temperament,” in which all semitones are equidistant, opened previously unheard of possibilities for Bach. The innovations it gave rise to, found their way even into his works for solo string instrument. Many of the arpeggios and various double stops in those pieces employed such sonorities, from which Bach could deviate into an array of keys. This would not have been possible before the new tuning system.