Situating her argument in the debates between Luce Irigaray and Judith Butler over efforts to resuscitate the meaning and role of matter in the history of philosophy, Trott argues for a robust sense of matter in Aristotle’s account of generation. Specifically, Trott argues that form in the figure of semen in Aristotle’s account of generation is dependent on material power to do its work. This argument shows how matter has its own power in Aristotle in such a way that makes the relationship of form to matter in Aristotle’s causal structure akin to that of a Möbius strip. The book establishes a positive contribution of material, which Aristotle associates with the female, while also showing the dependence of form, which Aristotle associates with the male, on the material power of elemental forces, specifically of heat.