The transformation of the _genre_ of the French grand opera had begun with Auber's _La Muette de Portici_, performed in 1828. _La Muette_ was the first work conceived in the new forms and in the vast proportions of the school which was to succeed the school of Gluck and his followers. The scenic development, the pursuit of new and piquant harmonies, the importance given to the orchestra; all this, joined to a more varied and less uniform melodic expression, had produced a deep impression on the public, and dethroned with a single blow the ancient opera which had reigned for more than half a century. Rossini had come later with his _William Tell_, in which the splendor of the style, the richness of inspiration and the fullness of dramatic expression, all carried to their highest degree, had marked an advance over the remarkable work of the French composer, without, however, surpassing the latter's elegance and originality. With _Robert le Diable_, Meyerbeer, in his turn, struck a note entirely personal, and in this work the passionate vigor of accent, the power of orchestral combinations, the particular character and relief given to each of the personages, indicated a musician of a new and profoundly original genius; a genius more complex than that of his predecessors, seeking for effects in the detail as well as in the _ensemble_, but arriving like them, and by different means, at an intensity of expression which was difficult to surpass. It goes without saying that the score of _Robert le Diable_ contained suggestions of the forms adopted by the author in the course of his Italian career. This is especially noticeable in the first act and the beginning of the second, and it would not have been an easy matter to avoid it. But the general style of the work has an incontestable grandeur, the declamation, noble and powerful, assumes the character of the French lyric declamation, the contrasts of situations are striking and managed with a remarkable intelligence, and the color of the music, its fantastic character, so well in accord with the subject, are of such an intensity as to produce on the hearer an ineffaceable impression. It is in the third act especially, divided into two distinct parts, that the genius of the composer is given full scope, and attains its most complete magnificence. The comic scene between Bertram and Raimbaut, that in which voices from below call to Bertram, the dramatic scene between Bertram and Alice, are all of a great beauty, and the tableau following, that of the evocation of nuns in the depth of their cloister, with the episode of the seduction of Robert, is of a wonderful poetry and grace, and contrasts in a striking manner with that which precedes. In the fourth act it is the human passion which speaks its most pathetic language from the grand duet of Robert and Isabelle to the moment when the powerful finale comes to prove to us that Gluck's genius and his transports are not unknown to the genius of Meyerbeer.