In Chapter 14 of Peter Pan, the narrator uses a "vain tabernacle" as a metaphor for the average human being:
Hook trod the deck in thought. O man unfathomable. It was his hour of triumph. Peter had been removed for ever from his path, and all the other boys were on the brig, about to walk the plank. It was his grimmest deed since the days when he had brought Barbecue to heel; and knowing as we do how vain a tabernacle is man, could we be surprised had he now paced the deck unsteadily, bellied out by the winds of his success?
"Tabernacle" has two primary definitions. The first is a portable dwelling of light construction. The second is a meeting place for worship. For example, in the Bible, Moses builds a tabernacle as a place of worship according to a pattern shown to him by God as a sort of copy or shadow of what will be in heaven. For the purposes of this analysis, a tabernacle is a flimsy construction that cannot withstand any kind of challenge to its structural integrity.
In Barrie's work, the "vain tabernacle" of man serves as a metaphor that emphasizes the vanity and temporality of human beings, which, much like superficial structures made to imitate heaven, are themselves imperfect and earthly. In this particular scene, Captain Hook paces the deck of his ship as he contemplates his future triumph over the Lost Boys. The narrator compares him to a "vain tabernacle" in order to show how portable—changeable—his opinions and feelings can be. Will Hook let the Lost Boys walk the plank, or won't he? Will he fulfill his most evil potential, or will he show a bit of mercy? The metaphor of the tabernacle permits greater insight into Hook's character and reveals that he is not purely evil, as he has the potential to change. He berates himself for these wavering thoughts, but compassionate readers might identify them as signs of flexibility, rather than flimsiness.
In the midst of a sword fight between Captain Hook and Peter Pan in Chapter 15, Peter describes himself with a telling metaphor:
“Pan, who and what are thou?” he [Hook] cried huskily.
“I'm youth, I'm joy,” Peter answered at a venture, “I'm a little bird that has broken out of the egg.” This, of course, was nonsense; but it was proof to the unhappy Hook that Peter did not know in the least who or what he was, which is the very pinnacle of good form.
Here, Peter claims to be three things: youth, joy, and "a little bird that has broken out of the egg." The first two items represent more abstract concepts, and the third refers more specifically to a free bird. Why might Peter describe himself as a metaphorical bird? He can fly. The Never birds seem to consider him one of their own. And most importantly, Peter breaks out of society's restrictive shell in order to escape to Neverland. The fact that this metaphor appears in his own bit of dialogue demonstrates Peter's self-awareness. The narrator later claims that "good form" consists in having no idea who or what one is, but Peter at least knows that he embodies nature, youth, and freedom.
One might expect a child to be terrified of the evil pirate Captain Hook. But Peter finds strength in his own childlike qualities; he stands for youthful and joyful experience and takes great pride in his immortality. Later in the same passage, the narrator extends the metaphor by describing how "Peter fluttered round him [Hook]" and "darted in and pricked." These active verbs show that Peter shares some mannerisms and physical characteristics with birds. The metaphor shows that Peter might relate more to animals than humans, and that he remains more of a child than a man, but he still has that uniquely-human capacity of self-definition.