In the Tang Dynasty in China, there was a famous zen master who could enlighten others with a simple gesture. Whenever a spiritual seeker approached him to ask about enlightenment, the master would simply hold up his index finger and the seeker would become enlightened.
There was a young monk in the master’s monastery who thought this was all too funny and decided to copy his master. Whenever someone approached him to ask about enlightenment, the young monk would also hold up his index finger. The master got wind of this and decided to teach his disciple a lesson.
One day, the master called the young monk over and asked him “what is enlightenment?” When the young monk held his index finger out, the master swiftly chopped it off with a knife! Before the young monk could even scream, the teacher shouted “What is enlightenment?” The student, by force of habit, held up his index finger which was now vacant with emptiness, and was instantly enlightened.