As an old Goat was going forth to pasture, she carefully latched her door, and bid her kid not to open it to any one who could not give this pass-word: “Beware of the Wolf and all his race.” A Wolf happened to be passing, and overheard what the old Goat said. When she was gone, he went to the door, and, knocking, said: “Beware of the Wolf and all his race.” But the Kid, peeping through a crack, said: “Show me a white paw and I will open the door.” As the Wolf could not do this, he had to depart, no better than he came.
Two sureties are better than one.
Aesop