Cheating: it sullies the world of sport, ruins reputations, tears families apart, and can get you a lot of student loan money, but what does it have to do with playing the piano?
Well, a lot actually! Cheating, roughly defined right now by me, is the act (or art) or re-writing music for technical convenience, ie, to make it easier to play or execute. Now, a lot of self-called purist-types will frown conceitedly on the very idea of cheating in music. They usually come from the heretofore discussed "authentic" school of performance that holds a composer's intentions and historical accuracy in the highest regard. Like the whole idea of "authentic" or "accurate" performance, however, their concerns over cheating are misguided and impractical.
Cheating can be a pianist's best friend, but only when done with care and consideration. Pianist and Macarthur fellow Stephen Hough gave a series of classes the pianists at Northwestern last year. His first class basically devolved into a pianist's guide to cheating after his advice to three consecutive students, upon asking him specific technical questions, was more or less the same: "Oh I just re-write this section."
So when is cheating okay, and when is it not? As with any musical decision, the biggest (but not the only, as I'll explain) deciding factor is how it sounds. For instance, I confess that in my spring recital, I cheated a lot on this little ditty toward the end (excerpt shown above), as Chopin's writing for the left-hand is borderline unreasonable. From 4:48 to the end is among the most difficult sections of music I've ever played; bringing out the melody over all the other notes going on is next to impossible, but it's significantly more possible if you cut the middle note from all the three-note left hand chords! Trust me, no one missed them, or ever noticed/commented on their absence.
Okay, well, that explanation took longer than expected. Coming up, why cheating matters so much in the Goldberg Variations, and when it's not okay, for visual reasons.