Occasionalism is a philosophical theory about causation which says that created substances cannot be efficient causes of events. Instead, all events are taken to be caused directly by God Himself. (A related theory, which has been called 'occasional causation', also denies a link of efficient causation between mundane events, but may differ as to the identity of the true cause that replaces them).Steven Nadler, 'The Occasionalism of Louis de la Forge', in Nadler (ed.), Causation in Early Modern Philosophy (University Park, PA: Pennsylvania State University Press, 1993), 57–73; Nadler, 'Descartes and Occasional Causation', British Journal for the History of Philosophy, 2 (1994) 35–54.