Some insight into the studies of our great composers may also be obtained by comparing together such of their operas or other elaborate vocal compositions with instrumental accompaniment as are founded on the same subject. Note, for instance, the love-story of Armida, taken by the compilers of the various librettos from the episode of Rinaldo and Armida in Tasso's 'Gerusalemme Liberata.' The story had evidently a great attraction for the musical composers of the eighteenth century. There have been above thirty operas written on it, several of which it might now be difficult to procure, nor would an examination of them perhaps repay the trouble. However, the operas on the subject composed by Lulli, Gluck, Graun, Handel, Traetta, Jomelli, Naumann, Haydn, Sarti, Cimarosa, Rossini, Sacchini, etc., would suffice for the purpose. Thus also, a comparison of several compositions depicting a storm--most of our masters have written such a piece--elicits valuable hints for the musical student. Compare, for instance, with each other the storms in Gluck's 'Iphigenia in Tauris,' Haydn's 'Seasons,' Beethoven's 'Sinfonia Pastorale,' Cherubini's 'Medea.' Even arrangements may illustrate the studies. Take, for instance, the arrangements of Vivaldi's violin concertos by J. S. Bach. It is, however, but seldom that eminent composers have occupied themselves with arranging the works of others. Instructive examples of this kind are therefore rare. It is recorded of some composers that they were in the habit of founding their instrumental works on certain poetical ideas. Haydn is said to have done this almost invariably. Schindler, in his biographical notices of Beethoven, states that the two pianoforte Sonatas, Op. 14, of Beethoven, were explained to him by the composer as representing a dialogue between two lovers. When Schindler asked the meaning of the motivo of the C minor Symphony, [Music]