It moves the way color moves. That preposterous notion was given life by Josef Albers in Interaction of Color, in which he uses simple demonstrations of juxtaposed colors to show how volatile color is, how unstable, how mobile.
Sometimes this freaks musicians out who maintain that they know for sure where a note is. My reaction: Really?
Then how can it be that a highly experienced artist comes into my studio and begins a rehearsal by announcing that there is a note in the work which he has played and recorded dozens of times that he has never been able to play in tune: What note? A specific A on the cello. Hmmm. Could it be that Dvorak had caused that very central tone to move around before bringing it back in that highly specific setting?
The book that inspired all my work with tone is called Sound and Symbol, in which Viktor Zuckerkandl demonstrates that, unlike the symbols we use to "read" music, tone does move. He was right. Maybe that's why he had to do his teaching in the liberal arts environment, where one can say things like that out loud.