It becomes brighter when the Inspector enters, this is them being opened up to the world.
At the beginning of Act 1 the Birlings are enjoying a toast to Shelia and Gerald's engagement. The conversation reveals that the family does not care about anyone but themselves. Arthur Birling believes `a man has to make his own way, has to look after himself and his family too". .
Birling begin a speech on community, he starts by saying `the ways some of these cranks talk and write now you"d think everyone has to look after everybody else, as if we were all mixed up together like bees in a hive- community and all that nonsense". The Inspector enters at this point because he is there to prove Birling's point wrong.
Priestly wanted the Inspector to appear to be threatening. `He wasn't a big man but he creates at once an impression of massiveness, solidity and purposefulness". Inspector Goole persuades the Birling's to confess to their crimes. Even his name has a ghostly form, he seems to know everything he is in control. It's almost as though he knows the future.
Inspector Goole's dress sets him apart from the Birling's. They are dressed to impress. `All five are in evening dress of the period, the men in tails and white ties, not dinner jackets". The women wear long formal dresses. The Inspector is dressed in a `plain darkish suit of the period". He is dressed smartly but he is not concerned with appearance. Priestly dressed the inspector in clothes from the year 1945 to show the audience that the inspector was from the future; almost saying he has come from a land where people joined together, a place that was better. This emphasised the difference in society between 1912 and 1945. This is shown in contrast to the outfits the Birlings are wearing; clothes from 1912. The costumes in the theatrical production use this to show the difference in timescale.
Mr. Birling believes its every man for himself, to look after number one, and not to care for poor people to forget about community.