Interesting to hear from Thomas Mark, direct. Have you considered writing a second book with more personal beliefs and methods? Apologies if I misunderstood your intent with the firmed hand and arm drop exercise. However, I must say that I found that to be the one significant exception to the books neutrality. Personally, I think it would be better either left out, or put side by side with an exercise where the arm creates freedom with sideways movement, while fingers actually move- for the sake of restoring objective balance. As it stands, I do feel that this one exercise is a notable exception to what is otherwise admirable neutrality. Having been shown such exercises (prior to reading your book, I stress) but never shown the alternative of moving fingers properly from a free arm, this style of exercise totally infected my basic concept for piano playing, until I learned the alternative role of arm movement that create freedom, rather than pass movement on to keys through the hand.
Also, while you're here, can I politely point out a couple of scientific errors? I don't know if you'll have already heard the same things (and please let me stress that I have tremendous respect for the book as a whole) but there are definable mistakes in the chapter about keyboard mapping. I learned a lot from the explanation of the body, but some of the science just wasn't accurate here.
Firstly, you state that due to kinetic energy being 1/2 mass times velocity squared, a small change in velocity can accidentally trigger a huge change in volume, due to proportionality to the square. This is true, strictly speaking, BUT very misleading. Once something is moving fast, what the equation actually means is that it takes substantially more energy to continue adding to the velocity. If something is at 5ms it take vastly more effort and energy to go from 5 to 6 than it does to go from 4 to 5 and especially 1 to 2. In other words, you don't accidentally push just a trace harder and suddenly have a huge explosion of energy due to the square. Rather if you push only a trace harder, you make a trace of change to the velocity.
Basically the whole square issue cancels itself out. Any impression that only a fraction more input from the finger makes for a collosal change in tone is down to a totally separate issue, as your basis is not technically accurate. The piano's level of tone is certainly NOT proportional to the square of the amount of effort that you input. If anything, it ought to be along the lines of a relatively straight direct proportionality.
The same underlying issue means that your dropping different masses analogy doesn't work. This time, the same equation is very much relevant. The more mass, the more energy. For the analogy it to work, we should be dealing in what happens when objects land and NOT their speed during unimpeded free fall. That is simply irrelevant. At landing, less massive objects are repelled more easily. When falling on a resistance plate (equivalent to resistance of a piano key) to a greater mass WILL pass on greater speed to that plate- as there is more energy to cut through that resistance.
For your analogy to apply, we must assume that, on landing, the exact same speed of an object is instantly transferred to whatever it contacts. That is most certainly not so- firstly because hands can either buckle back or positively create movement. They are not fixed structures. Secondly, even a stiff mass cannot pass on speed in the instant of contact- but the more mass, the more easily and rapidly its speed can be passed on.
In many ways, I agree that too much talk of mass is misleading, but your basis for trying to take it out of the picture isn't scientifically accurate.
Topic: arm or fingers : again