I always find it fascinating to consider 'touch' on instruments where there is not an immediate touching of the apparatus that generates the sound. A piano for example has all sorts of mechanical parts that are in play between the finger and the string. It's almost like the piano is playing the piano.
Not so on a guitar where the touch is immediate and seemingly more intimate. There's a part of my thinking that thinks that because of a piano's mechanical distancing between finger and string then how could there possibly be a distinciton in 'touch' between Bill Evans purposefully pushing down a key and a 5 year old kid accidentally bumping up against the very same key.
In other words "what's the difference that makes the difference" between those two examples. Is 'intention' the force that transcends the mechanical bridge between finger and string? When someone like Bill Evans touched the keys where was his intention? On the keys? On the strings? On the sound? Did it flow from place to place? I don't know but I've often wondered about this sort of thing.
Certainty is a feeling...not a fact.