Mr. Sullivan's task in setting these charming songs to music has not been without its difficulties. The very qualities which render verse characteristic of its author often militate strongly against its adaptability to music. The subtleties which form the main charm of the poet may be mere blemishes and hindrances to the musician. Irregularity of metre and variety of form are among his most serious difficulties. What the composer requires is a strong pervading sentiment or idea to inspire character to his music, with regular even verse for the vehicle. The finest songs of Schubert, Mendelssohn, and Schumann are written to little poems of the simplest structure, almost always in stanzas of four lines of eight or ten feet, the syllables linked together in easy concatenation. Such are the 'Auf Flügeln des Gesanges,' the 'Widmung,' the 'Junge Nonne,' and the 'Sey mir gegrüsst.' Was it instinct or calculation that led Goethe, Heine, Eichendorff, and other great poets of Germany, to throw so many of their enchanting thoughts and passionate emotions into these simple forms? Whichever it was, the end has fully justified the means; and the poems of these great geniuses have a double beauty and a double gift of immortality in the strains of their composer-brethren. Now the very charm of the songs of the 'Window' on which we have been insisting, and so rightly insisting, are all in opposition to those of the poems just spoken of. What is he to make of such stanzas as 'Gone! Gone till the end of the year, Gone! and the light gone with her, and left me in shadow here. Gone--flitted away'? or such unequal lines as 'Go little letter apace, apace, Fly!' or, 'For it's ay, ay, ay, ay, ay;' or, 'And my thoughts are as quick and as quick, ever on, on, on'? If we want to see what can be made of them, by what adroit shifts their difficulties can be avoided and overcome, we have only to turn to Mr. Sullivan's music; and the examination will well repay the trouble, and will open the eyes of anyone who was not before aware of the laws which must govern verse that is to be married to music. No. 6 has been altered since it was set, and we thus have the advantage of two versions. For the music itself we must really refer our readers to the book. Dissertations on music, unless in connection with actual performance, or with technical study, are very much like attempts to paint a sunrise in words. At any rate, without musical quotations, any description of these songs would be unintelligible.