As in the case of lines, you are likely to stop when you are no longer sure you should go further – at the rear edge of the region of uncertainty.*
Even within cultures strong on destiny, and social order and laws, there are trickster characters who help the people to playfully question the lines and to cross them.
We all need to find these tricksters and to learn how to be tricksters to others.
(*From Daniel Kahneman’s Thinking, Fast and Slow.)