There is a rabbi who asks his students, "When can we know that night has ended and the day begun?"
"It is the moment," one student proposes, "when you can tell the difference between a sheep and a dog?"
"No," says the rabbi.
"It is," asks another student, "when you can see the difference between a fig tree and an olive tree"
"Not that either."
The students ask in one voice, "Then what is it?"
The rabbi answers, "It is the moment when you can look at a face never seen before and recognize the stranger as a brother or a sister. Until that moment, no matter how bright the day it is still night."