Because the play has so few props, the props that do appear onstage take on an exaggerated significance. As one example, Vladimir, Estragon, Lucky, and Pozzo all wear hats and at times seem oddly preoccupied with them. Lucky, for instance, needs his hat to think, and stops his long monologue once his hat is knocked off. In act two Estragon and Vladimir exchange their hats and Lucky's hat back and forth, trying different ones on. Given the importance of these hats to their individual owners, this scene can be seen as representing the fluidity and instability of individual identities in the play. As Pozzo and Lucky don't remember having already seen Vladimir and Estragon in act two, Vladimir begins to wonder whether the Pozzo and Lucky of act two are the same as those of act one. Estragon, for one, does not recognize them, and calls Pozzo Abel. Estragon can't even remember his own past, and at one point tells Pozzo that his name is Adam. Moreover, it is not clear whether the young boy in each act is one boy or two different ones. The boy also calls Vladimir Mr. Albert, which may or may not actually be Vladimir's name. With all of this ambiguity and instability regarding people's identities, the scene of the hat exchange playfully represents an exchange of identities, as Vladimir and Estragon wear different combinations of hats. Vladimir ends up wearing Lucky's hat—notably, the one he needed to "think"—seemingly taking on a new identity, as he then asks Estragon to "play" at being Lucky and Pozzo. Indeed, it's uncertain whether Vladimir and Estragon (or other characters) are actually being themselves throughout the play, or if they even have stable selves they can be.