Interpretative liberties...

"During that time [1829-37], both at public concerts and in private salons (where people never failed to observe that I had selected my pieces very badly), I often performed the works of Beethoven, Weber and Hummel, and let me confess to my shame that in order to wring bravos from the public that is always slow, in its awesome simplicity, to comprehend beautiful things, I had no qualms about changing the tempos of the pieces or the composers's intentions. In my arrogance I even went so far as to add a host of rapid runs and cadenzas, which, by securing ignorant applause for me, sent me off in the wrong direction - one that I fortunately knew enough to abandon quickly. You cannot believe, dear friend, how mucho I deplore those concessions to bad taste, those sacrilegious violations of the SPIRIT and the LETTER, because the most profound respect for the masterpieces of great composers has, for me, replaced the need that a young man barely out of childhood once felt for novelty and individuality. Now I no longer diverce a composition from the era in which it was written, and any claim to embellish or modernise the works of earlier periods seems just as absurd for a musician to make as it would be for an architect, for example, to place a Corinthian capital on the columns of an Egyptian temple."

Liszt, 1837.