Tangen had studied with Sengai since childhood. When he was twenty he wanted to leave his teacher and visit others for comparitive study, but Sengai would not permit this. Every time Tangen suggested it, Sengai would give him a rap on the head.
Finally Tangen asked an elder brother to coax permission from Sengai. This the brother did and then reported to Tangen: "It is arranged. I have fixed it for you to start on your pilgrimage at once."
Tangen went to Sengai to thank him for his permission. The master answered by giving him another rap.