Describe symbolism in Curtain by Agatha Christie

The bird watching glasses represent seeing and perception. Norton is almost always carrying around the special glasses he uses for bird watching. They are a type of binocular. It is through these glasses that Norton claims to have seen something the might pertain to Mrs. Franklin's death. Hastings snatches the glasses away form Norton one day and Hastings thinks he sees a white gown rushing into the woods.