The interrogation of Eric, which begins this act, is the last in a chain of interrogations which have structured the play since the Inspector’s arrival (in order: Birling, Sheila, Gerald, Mrs. Birling, Eric). Each of the Birlings has played a part in Eva Smith’s death, and each of them must take part of the responsibility for what happened to her and for her final, sad choice. This motif, as well as the structure of the play and of Eva Smith’s life (though, to get the order of events right, Mrs. Birling was the last, not the penultimate, character to affect Eva in reality), points to two of Priestley’s key themes: the interrelationship of cause and effect and, more generally, the nature of time.
The “chain of events” that the Inspector outlined as leading to Eva Smith’s death in Act One is a key idea in the play. The chain of personal and social events is not simply a metaphor for the way the class system holds people like “Eva Smiths and John Smiths” firmly in their subservient positions in society, but it is also a neat encapsulation of the Inspector’s key moral: that everyone, contrary to what Birling explains, is indeed bound up with everyone else “like bees in a hive.” As much as we like to think of ourselves as individuals, we are also social beings.
The Birlings and Gerald Croft are chained together by Eva Smith’s death. Birling sets off the chain which makes possible Sheila’s bad deed against Eva, which in turn throws Eva into the path of Gerald and then Eric and, finally, in front of Mrs. Birling’s committee. Each deed is tied to the deed before it and the deed after it. The individual deeds, linked together, make Eva’s downfall so severe that she chooses suicide—effectively causing this choice. This is the “cause and effect” idea of succession that Priestley explores: the way in which time can indeed make us all responsible for each other.
Both of these