 Interest in metaphysical explanation has witnessed a recent spike, yet the topic is not a recent metaphysical innovation. Indeed, it is front and center in the very first sentence of the field’s foundational text, when Aristotle tells us that “All human beings by nature desire to know” (Metaphysics I.1, 980a21; see the entry on  Aristotle’s metaphysics).  For Aristotle, this desire is not fully satisfied until one understands the basic explanatory factors responsible for the broad structure of reality (see Lear 1988: chs. 1 and 6). Set aside whether Aristotle’s claim about human nature is correct. Even if it is not, a wealth of philosophical questions about the nature, varieties, and scope of metaphysical explanation emerge. Are these “explanatory factors” of one type or many, and what are they? What is it about “the broad structure of reality” that they explain? What type of understanding is gained by grasping these explanatory factors? And even if human beings by nature desire metaphysical explanations, to what extent (if any) can this natural desire actually be satisfied?