 The stronger, incompatibilist interpretation is that Aristotle did not believe that the behaviour of complex entities followed from the laws that govern their parts or their matter (Gotthelf 1987, Robinson 1983). By contrast, the behaviour of the matter is influenced by what it is the matter of. The nature of the matter places restrictions on what the enmattered thing can do—an animal can only be made from living tissue, not of stone or fire—but exactly how that matter behaves depends on the substantial form present in it. The substantial form plays, therefore, an essential role, not merely in certain kinds of scientific explanation, but by being a fundamental efficient cause in its own right. Whichever of these is the correct interpretation of Aristotle, it was the second that was the core of ‘Aristotelian science’ as found in scholastic philosophy, and it was this aspect of the Aristotelian doctrine of substance that aroused most opposition amongst seventeenth century philosophers and scientists. They insisted that bodies behave as they do because of the mechanical consequences of the nature of the matter from which they are made: the matter is not ‘pushed around’ or organised by a substantial form. Philosophers and scientists of the seventeenth and eighteenth centuries believed that in rejecting such influences they were rejecting the Aristotelian doctrine of substance.