During the French Revolution a lawyer, a priest, and an engineer are all to be put to death by the guillotine.

The lawyer lies down, waiting for the blade to come down. When the blade drops it suddenly stops inches away from the lawyer's throat. Every watching agrees he can't be legally executed twice, so they let him go free.

The priest goes next and the same thing happens, the blade stops inches from his throat. Everyone watching agrees he was saved by divine intervention, so they let him go free.

The engineer is next, he stares up at the blade and suddenly he shouts out "Wait a second, I see your problem..."