A teacher gathered together his students and asked them: ‘How do we know the exact moment when night ends and day begins?’
‘It’s when, standing some way away, you can tell a sheep from a dog,’ said one boy.
The teacher was not content with the answer. Another student said: ‘No, it’s when, standing some way away, you can tell an olive tree from a fig tree.’
‘No, that’s not a good definition either.’
‘Well, what’s the right answer?’ asked the boys.
And the teacher said: ‘When a stranger approaches, and we think he is our brother, that is the moment when night ends and day begins.’