When Night Ends

A Rabbi gathered together his students and asked them:  “How do we know the exact moment when night ends and day begins

“It is when, standing some way away, you can tell a sheep from a dog,” said one boy. 

The Rabbi was not content with the answer. 

Another student said:  “No, it is when, standing some way away, you can tell an olive tree from a fig tree.”

“No, that is not a good definition either.”

“Well, what is the right answer?” asked the boys.

And the Rabbi said:  “When a stranger approaches, and we think he is our brother, that is the moment when night ends and day begins.”