  Although persons have proper parts, the property of being a person (which McTaggart calls personality) is a simple, unanalyzable  quality.[21] Although the self is, in a sense, a bundle of mental states, not every bundle of mental states is a  self.[22] We are acquainted with the property personality, and contra Hume, Bradley, and perhaps Bertrand Russell, each of us is acquainted with something that has this property, namely oneself.