exchange of his hat for Lucky's, thus signifying Vladimir's symbolic desire for another person's thoughts." These characterizations, for some, represented the act of thinking or mental state (Vladimir) and physical things or the body (Estragon). This is visually depicted by Vladimir's continuous attention to his hat and Estragon to his boots. While the two characters are temperamentally opposite, with their differing responses to a situation, they are both essential as demonstrated in the way Vladimir's metaphysical musings were balanced by Estragon's physical demands. The above characterizations, particularly that which concerns their existential situation, are also demonstrated in one of the play's recurring themes, which is sleep. There are two instances when Estragon falls asleep in the play and has nightmares, about which he wanted to tell Vladimir when he woke. The latter refuses to hear it since he could not tolerate the sense of entrapment experienced by the dreamer during each episode. This idea of entrapment supports the view that the setting of the play may be understood more clearly as dream-like landscape, or, a form of Purgatory, from which neither man can escape. One interpretation noted the link between the two characters' experiences and the way they represent them: the impotence in Estragon's nightmare and Vladimir's predicament of waiting as his companion sleeps. It is also said that sleep and impatience allow the spectators to distinguish between the two main characters, that sleep expresses Estragon's focus on his sensations while Vladimir's restlessness shows his focus on his thoughts. This particular aspect involving sleep is indicative of what some called a pattern of duality in the play. In the case of the protagonists, the duality involves the body and the mind, making the characters complementary. Throughout the play the couple refer to each other by the pet names "Didi" and "Gogo", although the boy addresses Vladimir as "Mister Albert". Beckett originally intended to call Estragon "Lévy" but when Pozzo questions him he gives his name as "Magrégor, André" and also responds to "Catulle" in French or "Catullus" in the first Faber edition. This became "Adam" in the American edition. Beckett's only explanation was that he was "fed up with Catullus". Vivian Mercier described Waiting for Godot as a play which "has achieved a theoretical impossibility—a play in which nothing happens, that yet keeps audiences glued to their seats. What's more, since the second act is a subtly different reprise of