„In the intellectual market the quantity of the demand rises in proportion to that of the supply, but its quality does not keep pace with this increase. For example, the Old Testament of pianoforte players, Bach’s “Wohltenoerurtes Klavier” is perhaps in almost as many hands as the New Testament, Beethoven’s Pianoforte Sonatas, but in few more heads than it was in former years, when it could only be had for six times the present price. Doubtless, its leaves are somewhat oftener turned over, but now, as then, about the sixth part, likely enough just the first sixth, is all that is studies in the real meaning of the word. Here truly is little more gained than a merely superficial acquaintance with the great father of German music.“
— Hans von Bülow
Preface to Instructive ausgabe. Klavier-Etuden von Fr. Chopin, 1880.