The Garden Party, by 17th century painter Esaias van de Velde, looks like your typical gathering of rich people out on a nice day, what with the light refreshments, table, servants, and amazing hats and shoes. Sure, the men look like they might spend their evenings waiting in dark alleyways to stab you and take your wallet, but now, everything is sunshine and pleasant company.
...Except some of the company are ghosts. Who are these spirits, absorbed in their own conversation? Why are they here? Were they killed in a carriage accident on the way to the party, and decided it would be a waste of a perfectly nice afternoon to cross over just yet? The glass cases in the front of the picture appear to be empty; are they really full of ghost food? Is the party really a séance gone awry, and they are hanging out for the show? Are they just waiting for the Ghostbusters to be invented? The world may never know.