 To expound the theory Pickup uses the terminology of a “person space”, an imagined realm of all possible persons, which is just “an abstraction of the facts about possible personhood” (422). A point within person space is “a representation of a group of properties that are jointly necessary and sufficient for being a certain possible person” (423). This is supposed to help us “see the conceptual space between being a certain person and being a certain entity” (422, n. 18). Pickup gives some non–theological examples to motivate the idea that one thing may occupy multiple points of person space: the fictional example of Dr. Jekyll and Mr. Hyde, and humans suffering from Dissociative Identity Disorders (420–1).