Aristotle was the first philosopher to offer a systematic account of luck (hê tuchê) and to include it as a significant topic in both physics and ethics. In the Physics he complains that his predecessors, although they treat luck as a cause, have not explained its relation to art, nature, and necessity: ‘they all speak of some things happening by luck and others not, and so they should have at least taken some note of these things’ (196a15–17). Thus Aristotle repeatedly calls for an investigation of luck and the wider phenomena of spontaneity (to automaton). This he delivers not only in Physics 2.4–6, but also in several other stretches of natural philosophy (APo. 1.8–11; Cael. 2.6; GA3.11; Metaph. 7.7–9). In his ethics, Aristotle blazes a parallel dialectical trail. Although the predecessors mentioned luck in their ethical discussions (Aristotle himself refers to Socrates in Plato's Euthydemus), no one before Aristotle defined luck or explained how it relates to the causes of happiness. Aristotle, however, explicitly framed the problem of moral luck in several sustained discussions (EN 1.9–11; EE 7.14; MM 2.8). In physics, Aristotle walks a middle course between one extreme of making luck and spontaneity the causes of everything in the universe, and another extreme of eliminating these causes. Thus although Aristotle refuses to recognise any spontaneous occurrences in the heavens, he theorised many spontaneous phenomena in the meteorological and terrestrial zones, for example, accepting that some plants and animals are generated spontaneously. But he insists that most and the most important living things require reproduction of natural forms and he insists that neither spontaneity nor luck could possibly account for those things.