 Hasker spends several chapters (25–8) addressing the question: “in virtue of what do the three persons constitute one God?” (203). The three enjoy some sort of unity of will and fellowship, and they are united in that the second and third exist and have the divine nature because of the first, but such factors don’t, by themselves, imply that they somehow amount to a single god. Hasker holds that a crucial factor is the idea of their shared divine nature as a concrete property or trope. Following Craig, sometimes Hasker characterizes this concrete divine nature as a divine mind or soul. He argues that for all we know, it is possible for one such trope of divinity “to support simultaneously three distinct lives” which belong to the Persons (228). He argues that this possibility is indirectly supported by split-brain and multiple-personality phenomena in human psychology. He takes these to show that “It is possible for a single concrete human nature–a single trope of humanness–to support simultaneously two or more centers of consciousness” (236).