While the choice of words and sentences used in dialogue is important, punctuation can often show how people speak.
This is as important as what they say.
Mary’s hesitant speech, for example, reveals her growing awareness that Bentham never viewed her as a social equal, “I imagine ... he thought ... we weren’t ... good enough for him”.
O’Casey suggests through the use of ellipsis that she is only now realising this, we also feel her weariness and hopelessness about the situation.
O’Casey also uses ellipsis to great effect in the final scene of the play where the disintegration of the Boyle family, and Captain Boyle’s inability to cope with reality, is conveyed by his drunken speech.
He and Joxer’s inarticulate musings are broken up by more ellipsis as the conversation progresses, highlighting this breakdown and their increasing drunkenness. The scene culminates in Boyle's observation - repeated frequently in the play - that “th’ whole worl’s … in a terr … ible state o’ … chassis!”.