Inspector Goole's final speech is delivered almost as a sermon. He has given the impression throughout the play that he is at least detached from, or above the other characters. The pun on the name Goole/ghoul suggests ghostly qualities as does the intimation of the events being re-run at the end of the play. His ability to hone in on each of the private guilts of the other characters seems beyond mere detective work.
'We are responsible for each other...If men will not learn that lesson, then they will be taught in fire and blood and anguish.'
This gives us an insight into the true moral purpose of the Inspector's visit. He is not merely investigating a suicide, or solving a series of petty crimes and social injustices, he is tying each member of the cast together in a web of social responsibility.
Towards the end of the play, the Inspector makes a speech, which outlines his political views. He says that we should look after each other and stop thinking about ourselves so much, 'We don't live alone. We are members of one body. We are responsible for each other.' This just shows how extreme his belief in socialism is and how he thinks people should live. He tried to teach the Birling's this through what he says and tried to force socialism on them. We see these beliefs right from when the Inspector is introduced into the play. Priestley uses the Inspector's entrance into the play to present and highlight the Inspector's socialist beliefs.