A mussel was sunning itself by the river bank, when a bittern came by and pecked at it. The mussel closed its shell and nipped the bird's beak. Hereupon the bittern said, ' If you don't let me go today, if you don't let me go tomorrow, there will be a dead mussel.' The shell-fish answered, ' If I don't come out today, if I don't come out tomorrow, there will surely be a dead bittern.' Just then a fisherman came by and seized the pair of them."
The moral of which word to the wise will be sufficiently obvious to the youngest reader.