bye-bye, free will
As it turns out, Leibniz' "two clocks" example is pretty different from how I remembered thinking about it when I read Bertrand Russells History of Western Philosophy, but it's still interesting:
-- Leibniz.The souls follow their laws, which consist in a definite development of perceptions according to goods and evils, and the bodies follow theirs, which consist in the laws of motion; nevertheless, these two beings of entirely different kind meet together and correspond to each other like two clocks perfectly regulated to the same time. It is this that I call the theory of preestablished harmony, which excludes every concept of miracle from purely natural actions and makes things run their course regulated in an intelligible manner.
(Here's the article I boosted it from.)