This chapter introduces the subjects which will be discussed over the course of the book. The question of personal ontology – “what are we?” – is distinguished from the more commonly discussed question of personal identity over time – “under what conditions is someone at one time identical with something at some other time?” This chapter introduces the main thesis which will animate much of the book, namely that we are unable to choose between substance dualism and the thesis that we are composite physical objects, as the arguments on each side of the issue can be parodied. This chapter also introduces the concept of composition, as well as the thesis of composition as identity, and argues that composition as identity should be rejected. The chapter ends with brief summaries of the remaining chapters.