Angulimala the bandit chased the Buddha through the forest, intending to rob and kill him. The speed and endurance of the Buddha seemed endless. Angulimala was beginning to grow tired and angry. Exasperated, he shouted at the Buddha, "Slow down! Stop!"
The Buddha, not even winded, shouted back at Angulimala, "I cannot slow down - I already have stopped, Angulimala. You slow down and stop."
Angulimala didn't understand. "What? We are both still running through the forest."
The Buddha said, "I have stopped, Angulimala. I am no longer violent to any living being. You, though, are utterly unrestrained, without self-control."
Angulimala remembered something he heard when he was young, before his killing and robbing began. Suddenly, he became aware of what he had been doing, and what he was about to do. He stopped running right there, and threw down his weapons down and away. He knelt down right there in the forest, and greatly regretted everything he had done.
The Buddha stopped and approached Angulimala. Studying Angulimala only a moment, the Buddha helped Angulimala to his feet and said, "come, monk."
This was how Angulimala became a monk: he became aware, and acted in self-control according to that awareness.