He followed Ummon for eighteen years as his attendant. Every day Ummon called him, and when he answered, "Yes, sir!" Ummon would say "What is this?" This was continued for eighteen long years.
Then one day Kyorin exclaimed "Oh! I understand!".
Ummon said, "Why don't you say it in a transcending manner?" And Kyorin spent another three years with Ummon to attain full maturity.
He was a great master but slow to mature.