Unity of time (timescale is not more than 24 hours)
Unity of place (only one setting)
Greek Drama also often featured a Chorus (a character who commented on the characters and explained the lessons to the audience). This Inspector could be seen as the chorus as he teaches the audience a moral message of social responsibility. Greek drama also often had a didactic moral lesson to teach the audience, much like AIC does.
An Inspector Calls can also be seen as a Christian morality play, teaching a lesson about the Seven Deadly Sins.
Detective drama or whodunnit
In a traditional detective drama or whodunnit ,a mystery, frequently involving murder, is unravelled by the careful questioning of a detective.
The unresolved ending is where Priestley subverts the structure of both the Well-Made Play and the whodunnit.
He leaves the audience with questions at the end.
Ouespensky's time theory
he believed that when we die we live our life once more from the beginning. This cycle would keep repeating and only change different if we make some change or improvement in the way we live our life.
Dunne's time theory
he believed that time was not linear (not happening in one direction) so our subconscious mind may be able to sense both forward and backward in time, meaning people can have some awareness of the consequences of their actions.