Aristotle set up a whole taxonomy of causation, including “material causes,” “formal causes,” “efficient causes,” and “final causes.” For example, the material cause of the shape of a statue is the bronze from which it is cast and its properties; we could not make the same statue out of Silly Putty. However, Aristotle nowhere makes a statement about causation as a counterfactual, so his ingenious classification lacks the simple clarity of Thucydides’s account of the cause of the tsunami.