Over against the Gradus of Clementi, as a remarkable collection of the most varied pieces, stand certain smaller studies of a more defined physiognomy. The well-known “Préludes et Exercices” are written in all the keys, and keep on the whole to the scale-motive. The “Méthode du Pianoforte,” with its fifty lessons, collects all kinds of airs and old pieces, provided with marks of fingering--which, however, are very much behind those of Czerny. The book is noteworthy as one of the first important attempts to make use of already existing pieces, not the work of the collector, as material for studies. Very soon the sonatas of Beethoven appear in these collections, where they are arranged according to their difficulty. Here are Handel, Corelli, Mozart, Couperin, Scarlatti, Pleyel, Dussek, Haydn, Paradies, and the Bachs. Clementi sowed his wild oats in a series of preludes and cadenzas which he published (Op. 19) under the title of “Characteristic Music.” These were written in the styles of certain masters and other famous clavier-teachers, such as Haydn, Kozeluch, Vanhall, Mozart, Sterkel, and Clementi himself. It was half a jest, and a very moderately successful one; but it is worth noticing as a sign of an interpretative and compiling tendency. Among the hundred sonatas and sonatinas, for one or two players, which Clementi left behind, there is not a single one without interest or utility from the standpoint of instruction; but from that of content there is at most only one which can to-day attract us by its originality or genius. This is the so-called Dido sonata, dedicated to Cherubini; and even in it the genius is cold. In the other sonatas we see the body of a Beethoven without the soul. It is Scarlatti once again--trivial and soul-less; but unlike Scarlatti, who cut short what had a short life, it is pretentious in its eternal repetitions. It is a manufacture of music, nourished by the didactic spirit: compared with the full effects of Hummel it is an empty style. [Illustration: J. N. Hummel. Engraved by Fr. Wrenk (1766-1830), after the portrait by Catherine von Escherich (beginning of 19th century)]