You know the basis for most horror films.You know,everything is fine,then weird things happen.The house doors lock,so on.

That was a old Italian horror novel from 1836 .I forgot the name. In the Novel,everything is going well,then weird things start happening. At the main character's son's wedding,for instance,a giant helmet falls out of the sky,crushing his son,the suitor.

If you compare this to modern films,you notice the similarities. In the film Gallows,a group of students end up stuck in a school were the ghost of a dead student haunts them.

They both have the same outline.The character(s) are going about their business,then their particular activity goes wrong ,abnormally wrong.

So,that is my thought about horror films.Now let me depart (pun)to watch Poltergeist.😀