When you can take the pebble from my hand.....
In the 70s tv show Kung Fu the student knew from an early age that when he was fast and strong enough to take the pebble from his master's open hand before he could close his fist that "it is time for him to leave".
Here we are now, present day, and we are living in what economists call "The Sandwich Generation" where homeowners are supporting (1) thier aging parents and also (2) adult children moving back home because of failed marriages or careers......makes me wonder if the kung fu master actually closed his hand slow so he wouldn't have an army of adult students living for free in the basement :)