In order to get a clear idea of the present state of the matter we must review the question from the beginning of the eighteenth century. For many reasons this is not an easy task, first of all because very little of the music of the operas of this period actually exists. We know the names of Hasse, Pergolesi, Matheson, Graun, Alessandro Scarlatti (who was a much greater man than his son the harpsichord player and composer, Domenico), to name only a few. To be sure, a number of the French operas of the period are preserved, owing to the custom in France of engraving music. In Germany and Italy, however, such operas were never printed, and one may safely say that it was almost the rule for only one manuscript copy to be available. Naturally this copy belonged to the composer, who generally led the opera himself, improvising much of it on the harpsichord, as we shall see later. As an instance of the danger which operas, under such conditions, ran of being destroyed and thus lost to the world, we may cite the total destruction of over sixty of Hasse's operas in his extreme old age. The second point which makes it difficult for us to get an absolutely clear insight into the conditions of opera at the beginning of the eighteenth century lies in the fact that contemporary historians never brought their histories up to their own times. Thus Marpurg, in his history, divides music into four periods; first, that of Adam and Eve to the flood; second, from the flood to the Argonauts; third, to the beginning of the Olympiads; fourth, from thence to Pythagoras. The same may be said of the celebrated histories of Gerbert and Padre Martini. On the other hand, we are certain that much of the modern speculation was anticipated by these men. For instance, Matheson calls pantomime "dumb music," freed from melodic and harmonic forms. The idea was advanced that music owes its rhythmic regularity and form to dancing, and architecture was called frozen music, a metaphor which, in later days, was considered such an original conception of Goethe and Schlegel. This same inability of historians to bring their accounts up to the contemporary times may be noticed in the later works of Forkel (d. 1818) and Ambros (d. 1876). Yet a third reason remains which tends to confuse the student as to what really constituted opera. This is owing to the fact that there existed the very important element of improvisation, of which I shall speak later. In order to see what Gluck, Weber, and Wagner had to break away from, let us look at the condition of opera at the beginning of the eighteenth century. We remember that opera, having become emancipated from the Church long before any other music, developed apace, while instrumental (secular) music was still in its infancy. In Germany, even the drama was neglected for its kindred form of opera; therefore, in studying its development, we may well understand why the dramatic stage considered the opera its deadly enemy.