When Schumann wrote in his review of the first performance of Mendelssohn's Overture Das Märchen von der schönen Melusine ( Gesammelte Schriften, 1914, Vol. I, p. 144):
". . . At first we thought that the Overture was written intime; the too rapid tempo of the first performance, which took place in the absence of the composer, was most likely responsible.time, however, which we saw later in the score, suggests a less passionate but more imaginative mood which keeps the player more relaxed; moreover, we think it is too broad and drawn out. To many this may seem insignificant, yet it is based upon an irrepressible feeling that in this case we can only utter but not prove . . ."
both the meaning of time signatures and the older system of accentuation had been forgotten. Musicians were no longer aware that: ". . . each time signature requires its own specific interpretation and has its own innate tempo . . ." ( Sulzer, Allgemeine Theorie der schönen Kunste, 1771-4, art. "Takt".)
It was just at this time that distinguished musicians and musicologists set out to edit the complete works of Bach, Handel, Haydn, Mozart and Beethoven. This formidable task, which was accomplished at the turn of the 19th century, requires the highest degree of musicianship, knowledge, experience and responsibility, qualities that not all of the editors possessed. Their efforts resulted in editions which bore the stamp of their own time rather than that of the composer's. It must be admitted that the difficulties facing an editor who endeavours to follow faithfully a composer's intentions are indeed considerable; one of the main problems is the decision on which source the edition should be based. In many cases an editor has to choose between the autograph or hand-written copies and the first or other early editions and a proper appraisal of early editions is often impeded by our still limited knowledge of the methods and customs of engraving in the past.
There is, for instance, the question whether the autograph or the first edition--in cases where they differ--contains the composer's final intentions. Similarly the editor must decide whether corrections and changes made in the autograph by the composer himself were made before or after the first edition was published. This last question arises with Mozart's six famous string quartets dedicated to Haydn.