In 1723 he obtained the position of Cantor at the St. Thomas School, in Leipzig, left vacant by the death of Kuhnau; here he remained until his death. In 1749 the English oculist, Taylor, happened to be in Leipzig. On the advice of friends, Bach submitted to an operation on his eyes, which had always troubled him. The failure of this operation rendered him totally blind and the accompanying medical treatment completely broke him down. On the eighteenth of July, 1750, he suddenly regained his sight, but it was accompanied by a stroke of paralysis from which he died ten days later. So far as his church music is concerned, Bach may be considered as the Protestant compeer of the Roman Catholic, Palestrina, with the difference that his music was based on the tonalities of major and minor and that his harmonic structure was founded on a scientific basis. What is mere wandering in Palestrina, with Bach is moving steadily forward with a well-defined object in view. With Bach, music is cast in the definite mould of tonality, while with Palestrina the vagueness of the modes lends to his music something of mystery and a certain supernatural freedom from _human will_, so prominent a characteristic of Bach's compositions. In considering Bach's music we must forget the technique, which was merely the outside dress of his compositions. His style was the one of the period, just as he wore a wig, and buckles on his shoes. His music must not be confounded with the contrapuntal style of his utterance, and although he has never been surpassed as a scientific writer of counterpoint, it would be unjust to look there for his chief glory. As a matter of fact, when his scientific speech threatened to clash with the musical idea in his composition, he never hesitated to sacrifice the former to the latter. Thus Bach may be considered the greatest musical scientist of his time as well as the greatest breaker of mere rules. Of his sons, Carl Philipp Emanuel is the most celebrated, and did much to prepare the way for Haydn in the development of the sonata. J.S. Bach wrote many sonatas, but none for the clavichord; his sonatas were for the violin and the 'cello alone, a great innovation. The violin sonatas bring into play all the resources of the instrument; indeed it is barely possible to do them justice from the technical standpoint. His "Wohltemperierte Clavier" naturally was a tremendous help to clavichord technique, and even now the "Chromatic Fantaisie" and other works require fine pianists to perform them properly.