"The feedback of voluntary activity is of this nature. We do not will the motions of certain muscles,..."

“The feedback of voluntary activity is of this nature. We do not will the motions of certain muscles, and indeed we generally do not know which muscles are to be moved to accomplish a given task: we will say, to pick up a cigarette. Our motion is regulated by some measure of the amount by which it has not yet been accomplished.”

- Norbert Wiener

from Stowe Boyd http://www.stoweboyd.com/post/145147940322