A priest, a drunkard, and an engineer were led to the guillotine for their crimes. The executioner pulled the priest forward first and asked him if he wanted to be facing up or down when he met his face.

"Upward," said the priest. "I want to be looking toward heaven when I die."

The blade zoomed downward, but stopped just an inch short of the priest's throat. All assembled agreed that it was divine intervention, and let the priest go free.

The drunkard was pulled forward next, and decided to copy the priest, hoping he would get as lucky. Again the blade zoomed down but stopped just short of the drunkard's throat. So the authorities released him as well.
It was finally the engineer's turn. 

He, like the others, decided to face upward. The blade slowly raised back into place. "Oh, hey, I think I know what the problem is." The engineer exclaimed.  "That cable to the left appears to be catching the rope!"