 Epiphenomenalism is the view that mental events are caused by physical events in the brain, but have no effects upon any physical events. Behavior is caused by muscles that contract upon receiving neural impulses, and neural impulses are generated by input from other neurons or from sense organs. On the epiphenomenalist view, mental events play no causal role in this process. Huxley (1874), who held the view, compared mental events to a steam whistle that contributes nothing to the work of a locomotive. James (1879), who rejected the view, characterized epiphenomenalists’ mental events as not affecting the brain activity that produces them “any more than a shadow reacts upon the steps of the traveller whom it accompanies”. 