The ending is important because it creates an unexpected climax which poses more problems than it solves. Throughout the play, the characters had been confronted by their moral frailty. They were forced to acknowledge their roles in Eva Smith's unfortunate and horrifying demise. Mr and Mrs Birling stubbornly refuse to accept their guilt, whilst Sheila, Eric and Gerald Croft acknowledge their role in the unfortunate girl's suicide.

When inspector Goole leaves, the characters and the audience are taken on a roller coaster of discovery and surprise. The audience is especially drawn into the final events since a number of intriguing events occur. First there is Gerald's statement that he had discovered that the wily inspector was not a detective at all. One of the local policemen had told him that they had no inspector Goole at their office. This fact is confirmed by a phone call Mr Birling makes to the the station.

The older Birlings and Gerald express relief and are convinced that the whole thing was a hoax. Sheila and Eric, however, have a different perspective and insist that the fact that it was a hoax does not undo the bad that they had done and that they should accept responsibility for their actions. She recalls that the inpector mentioned that they had all killed Eva.

At this point, Gerald makes another astounding assertion: What if the girl mentioned was not the same in all cases? There is a great deal of discussion around the fact that none of the participants had seen the photograph of the girl together and at the same time. Geralsd suggests that they could all have been different girls. Sheila, however, is adamant that that still does not change anything. They were all responsible in determining the girl's fate, whether she was the same one or many different girls. Their guilt is the same and they have to show some remorse and be accountable.

Once this little discourse is out of the way, another conundrum pops up. Eric states that the girl he knew is dead and Gerald counters by asking what if no one had died that day? What if it was all made up as part of inspector Goole's elaborate hoax? The issue is quickly resolved when Gerald phones the infirmary to establish whether any victim featuring Eva's circumstances and description had been brought in that day. When the reply is negative, Mr Birling expresses relief and says the whole incident had been just a lot of moonshine. It was bunkum.

Sheila and Eric, however, seem to be the only rational ones in the room. They both agree that even that does not mean anything. Nothing has changed since all of them still did the wrongs that they had done. Nothing can change that. She, especially, is quite disgusted by her parents' and Gerald's reactions. They seem to believe that since there is no body, they are in the clear - not guilty.

In an amazing and climactic twist in the tale the group discover, through a phone call from the local police station, that a girl has just died on the way to the infirmary after swallowing disinfectant. A police inspector is on his way to to ask them a few questions. Both the audience and the characters in the play are left dumbfounded as the curtain falls.

The ending dramatically illustrates our folly once we are in denial. The fact is that nothing can change the wrongs that we did. Circumstances and conditions may change, but the deed/s remain. The best that we can do is to seek redemption and, for that to happen, we certainly have to accept blame. Our pasts may catch up with us and we will then be forced to reconsider our attitudes.

As the curtain falls, the audience is left to ponder about how our characters will respond to the devastating truth. Will they have learnt from the mistakes they made during inspector Goole's scrutiny or will they humbly accept and apologise for the wrongs they did? That, truly, is the question. 

Well, let's look at the ending, and then try to figure out why it's important. Here are Goole's last words before he leaves the house:

We don’t live alone. We are members of one body. We are responsible for each other. And I tell you that the time will soon come when, if men will not learn that lesson, then they will be taught it in fire and blood and anguish. ... Good night."

The family members quickly forget their own guilt in favor of figuring out the identity of the inspector. As it turns out, their own investigation reveals there IS no "Inspector Goole." Such is a play on the character's name: goole/ghoul. He is a "ghost" of sorts: a ghost of forewarning. For suddenly there is a final phone call. A girl is dead after swallowing disinfectant, ... and an inspector is on the way!

There is something supernatural at work here, more than just a fortuitous circumstance. This "ghost," this "ghoul," this "Goole" has a moral purpose here. Goole is not trying to solve a simple crime, he is trying to give each member of society (and of this family, specifically) culpability for this death.

Still, the curtain falls before the "real" inspector arrives. We, as watchers (or readers) are meant to wonder how the family will truly react. Will they learn from their experience? Or will they fail once again?

What is important about the ending is that, after the Inspector leaves the play, the characters very quickly show that they have ignored or forgotten the lesson of his visit. Note how at first they try to recover their own sense of hurt and guilt from their involvement in the blame that has just been apportioned to each of them. However, very quickly, and perhaps too quickly, they then turn away from their own guilt and involvement and begin to think about the Inspector.

It would be so easy for them to dismiss the evening's "entertainment" as some kind of stunt and carry on with their lives without really allowing the events of that evening to change them. Gerald's discovery that there is no such individual as Inspector Goole gives them all a sense of relief that suggests this very outcome. Thus the ending is vitally important in not letting the characters off the hook. They must face their own guilt and involvement in the death of Eva Smith. They have had to face this now already, but will they respond in the same way? The audience is left to ponder these questions as the curtain falls.