When Night ends and Day begins?

One day a master asked his disciples how they could tell when the night had ended and the day had begun.

One of them said, ‘When you can look in the distance and tell whether the animal is a cow or a horse.’ The master said, ‘No.’

Another disciple said, ‘When you can look at a tree in the distance and tell if it is a pine tree or a mango tree.’ The master again said ‘No.’

They asked the master, ‘Then what is it master?’
The master replied, ‘When you can look into the face of any man and recognize your brother in him. When you can look into the face of any woman and recognize your sister in her. If you cannot do this, then no matter what time of the day it is, it is still only night time.’