There are three kinds of knowledge: bookish knowledge, discriminative knowledge, and practical knowledge. Bookish knowledge is superficial. Discriminative knowledge enables us to know what is real and what is unreal. Practical knowledge is experiential knowledge. Practical knowledge starts with discriminative knowledge. A small amount of experiential knowledge is sufficient. As long as we are dependent on the external world, we cannot have experiential knowledge. Once, a traveller was carrying a bundle of food on his head. He walked a short distance. As the bundle was a burden on him, he could not walk far. On the way, he came across a river. He sat down on its bank, opened his bundle and ate all the food. As long as the food was outside, it was a burden. Was it still a burden after it reached his stomach? No. As the food entered his body, he gained strength. Besides, he was relieved of his burden too. External knowledge is superficial and burdensome; internal knowledge is experiential knowledge. What is the use of studying a lot without knowing who you are? Modern education leads only to argumentation, not to total wisdom. What is the use of acquiring education which cannot lead you to immortality? Acquire the knowledge that will make you immortal.