When we started writing "23", we had been talking a lot about fugue states--psychological phenomenon wherein people inexplicably wander off from their lives and find themselves somewhere else later, with no recollection of the time in-between. (I think it started, actually, from talking about the use of fugue in music, where various melody lines work together to create a single, complex melody).
Those two ideas started jumping into each other, and we already had this kind of fractured musical composition written, so it seemed like an appropriate fit. For the verses, we wanted to identify with a person just coming out of a fugue state, having suddenly come to the realization that he was running, from something, to god knows where. The choruses sort of became the character's conscience, or what have you, reflecting on the absence of self-knowledge and the sudden realization that where they are heading is not where they had been, and that there seemed to be some agitation as a result. The subtitle "The Evolution of Flight" was an attempt to recognize the human mind's complicated escape mechanisms, and how our ability to flee has evolved along with our frantic times. The various spasms, disconnects, and breakdowns in the song are an attempt to make concrete the fractured psychological condition of the narrator, and the sort of varying messages each of us has in our mind at any given time.