After the first silence the small man said to the other: 'Where does a wise man hide a pebble?'
And the tall man answered in a low voice: 'On the beach.'
The small man nodded, and after a short silence said: 'Where does a wise man hide a leaf?'
And the other answered: 'In the forest.'

The Innocence of Father Brown (1911) 'The Sign of the Broken Sword'