Slow Practice

Charles Koeppen wrote, among other interesting things:

"Practicing slow can assure that you get the notes and tone right, but it doesn't assure that you'll keep your fingers loose and relaxed, try practicing something fast, preferably something you can play correctly at the quicker tempo. But, if you've already mastered something and want to reinforce it, or just want to loosen up, play it up to tempo."

I think these comments miss the point of "slow practice". In the first place if you can play something "correctly at the quicker tempo", if "you've already mastered something", you have no need to practice it, slow "or" fast. (I don't call reminding oneself that one can still play something "practice") More importantly, while it is true that one can be slow and tense, my suggestion has always been - if you can't play something at the speed required or desired, play it at the speed that you inherently know is easy. If you truly do this there is no reason at all why your fingers will be tense. If you then imitate that feeling at increasing speeds (which implies imagining the new speed before actually playing it) you will be building on success and will carry your confidence to new areas. You will also immediately sense any change in the quality of your movements. I hate to call this "slow practice" which seems to suggest some sort of drudgery. It's just sensible practice. There is no need to repeat a passage at the same speed as has been already achieved, and the progress from "slow" to "fast" can happen in minutes, not hours.