As it seems to me, it is only from the eighteenth century that authors have indicated the movements of their compositions, but the words which they have employed have changed in sense with time. Formerly the difference between the slowest movement and the most rapid movement was much less than at present. The "largo" was only an "adagio" and the "presto" would be scarcely an "allegro" to-day. The "andante" which now indicates a slow movement, had at that time its original signification, meaning "going." It was an "allegro moderate." Haendel often wrote "andante allegro." Through ignorance of that fact the beautiful air of Gluck, "Divinities of the Styx," is sung too slowly and the air of Thaos in the "Iphigenia in Tauris" equally so. Berlioz recollected having heard at the opera in his youth a much more animated execution of these works. Finally, in ancient times notes were not defined as they are to-day and their value was approximative only. This liberty in the execution of music is particularly perceptible in the works of Rameau. To conform to his intentions in the vocal part such music must not be interpreted literally. One must be governed by the declamation, and not by the written note indicating a long or short duration. The proof of this is to be seen when the violins and the voice are in unison--the way of writing them is different. A great obstacle to executing ancient works from the eighteenth century on is in the interpretation of grace notes, "appoggiaturas" and others. In these cases there is an unfortunate habit in players of conforming to their own taste, which may guide a little, but cannot suffice in every instance. One can be convinced of this in studying The Method of Violin by the father of Mozart. We find there things which one would never dream of. The "appoggiatura"[4] (from _appoggiare_, which in Italian means "to lean upon"), should always be long, the different ways in which it may be written having no influence upon its length. There is an exception to this when its final little note, ascending or descending, and preceding the larger note, is distant from it a disjointed degree. In this case it is not an "appoggiatura," and should be played short. In many cases it prolongs the duration of the note which follows it. It may even alter the value of the notes following.