The Principle of Agency says that if it would be good for a state of affairs to occur "naturally," then it is permissable to take action to bring it about. This contradicts the views of some bioethicists, who object to euthanasia, in vitro fertilization, and cloning, even though they acknowledge that the states of affairs produced are good. But the principle, or some form of it, seems inescapable. The opposite view -- that we may not, by our action, reproduce "natural" goods -- may owe its appeal to an implicitly religious view of nature.