An elderly rabbi once asked his students how one could recognize the time when night ends and day begins.  “Is it when from a great distance you can tell a dog from a sheep?” one student asked. 

“No,” said the rabbi.

"Is it when from a great distance one can tell a date palm from a fig tree?” asked another student. 

“No,” said the rabbi.

“When, then, how can one recognize that the night is over and day has begun?” the student asked.

The wise rabbi replied, “It is when you look into the face of any human creature, and see your sister or brother there.  Until then, night is with us.”

The wisest rabbi of all, Jesus of Nazareth, would agree.  He said, “Inasmuch as you did it unto the least of these, you did it unto me.”