dividing the two quick ones.  The three-movement form used by J.S.  Bach for his concertos and sonatas no doubt considerably influenced his son.  But already, in 1668, Diderich Becker, in his Musikalische Fruelings-Fruechte, wrote sonatas for violins, etc. and continuo, in three movements. (No. 10, Allegro, Adagio, Allegro.  Again, Sonata No. 19 opens with a movement in common time, most probably an Allegro; then comes an Adagio, and, lastly, a movement in six-four, most probably quick tempo.) These sonatas of Becker a 3, 4 or 5, with basso continuo, are unfortunately only printed in parts.  As a connecting link between the Gabrielis and Corelli, and more particularly as a forerunner of Kuhnau, Becker is of immense importance.  We are concerned with the clavier sonata, otherwise we should certainly devote more space to this composer.  We have been able to trace back sonatas by German composers to Becker (1668), and by Italian composers to Legrenzi (1655); those of Gabrieli and Banchieri, as short pieces, not a group of movements, are not taken into account.  Now, of earlier history, we do know that Hans Leo. von Hasler, said to have been born at Nuremberg in 1564, studied first with his father, but afterwards at Venice, and for a whole year under A. Gabrieli.  Italian and German art are thus intimately connected; but what each gave to, or received from, the other with regard to the sonata seems impossible to determine.  The Becker sonatas appeared at Hamburg, and surely E. Bach must have been acquainted with them.  Becker in his preface mentions another Hamburg musician—­a certain Johann Schop—­who did much for the cause of instrumental music.  Schop, it appears, published concertos for various instruments already in the year 1644.  And there was still another work of importance published at Amsterdam, very early in the eighteenth century, by the famous violinist and composer G. Torelli, which must have been known to E. Bach.  It is entitled “Six Sonates ou Concerts a 4, 5, e 6 Parties,” and of these, five have three movements (Allegro, Adagio, and Allegro).

Corelli was the founder of a school of violin composers, of which Geminiani,[4] Locatelli,[5] Veracini,[6] and Tartini[7] were the most distinguished representatives; the first two were actually pupils of the master.  In the sonatas of these men there is an advance in two directions:  sonata-form[8] is in process of evolution from binary form, i.e. the second half of the first section is filled with subject-matter of more definite character; the bars of modulation and development are growing in number and importance; and the principal theme appears as the commencement of a recapitulation.  We should like to say that binary is changing into ternary form; unfortunately, however, the latter term is used for a different kind of movement.  To speak of a movement in sonata-form, containing three sections (exposition, development, and recapitulation) as in binary form, seems a decided misnomer.