" She is standing just behind you. Just behind your right shoulder."
In the silence of the woods, Polly turned.
"I can't see her," she said.
"I am happy for you," said Wazzer, handing her the empty mug.
"But I didn't see anything," said Polly.
"No," said Wazzer. "But you turned around... "

― Terry Pratchett , Monstrous Regiment (Discworld, #31; Industrial Revolution, #3)