About 3,000 years ago, there was a young spiritual practitioner who was attending to an enlightened teacher. Due to his old age, his teacher could not chew very well. To feed his aged teacher, the disciple would chew the rice for him instead. The disciple realized that despite his efforts, he was swallowing most of the nutrition for himself. He felt terrible that he was taking in the nutrition that was meant for his teacher. He fervently searched for food that that his teacher could eat. As he was wise, he soon realized that soybeans were very nutritious. His first attempt was to grind the soybeans and boil them, and from that tupu was invented. The excess soybeans that were put into storage occasionally became wet. The wet soybeans grew sprouts, and that is how we came to have bean sprouts.