Newton said, "If we allow, not only the muscles, but the nerves, and even the brain itself, to be ‘pistons and cylinders, weights and springs’ as you put it, whose machinations might be observed and described by some future Hooke, then we must still explain how those mechanisms are informed by the soul, spirit, or whatever we are going to call it—the thing that has free will, that is not subject to deterministic laws, and that accounts for our being human. This is ultimately the same problem as we discoursed of earlier—the problem you find boring, Daniel—of God’s relationship to the Universe. For the relationship that our souls bear to our bodies, is akin to the relationship that God bears to the entire Universe. If God is to be something more than an Absentee Landlord—something more than the perfect watch-maker, who sets His clock a-run, and walks away from it—then we must account for how He influences the movements of things in the world. This gets us round to that mysterious phænomenon called Force. And when we discourse of animal motion we must in the end address a like problem, namely of how the soul that inhabits a body may influence the operation of what is in the end just a big soggy clock."