Tozan heard that a monk had once asked the National Teacher Nan’yo Echu ‘What is the mind of the ancient Buddhas?’ and Nan’yo had replied, ‘A wall tile’. Tozan didn’t understand what the National Teacher had meant by this. To him, perhaps taking the perspective of the Southern school, a wall tile was simply inert. He did not see that anything inanimate could expound the Dharma. So he asked Isan for guidance.