Some time ago -- a year, two years? -- I came across an article on the technical demands of music. I think it might have been linked to from Elaine Fine's blog, Musical Assumptions (to which I commend you anyway), but I can't find it there.
I remember quite clearly that it used a typing analogy, comparing playing music to copy-typing, but in a specific rhythm, in time with others, with precise pressure on each key according to how bold the letters are on the page, and having to get everything right. It went into more detail than that and explained the process far better than I can.
I can't find it anywhere. Has anyone seen it?