Day 21 covers all of Chapter 16, The Duration of the Life of the Tathāgata.
“I will tell you a parable. There was once an excellent and wise physician. He was good at dispensing medicines and curing diseases. He had many sons, numbering ten, twenty, or a hundred. [One day] he went to a remote country on business. After he left home, the sons took poison. The poison passed into their bodies, and the sons writhed in agony, rolling on the ground. At that time the father returned home. Some sons had already lost their right minds while the others still had not. All the sons saw their father in the distance and had great joy. They begged him on their knees, saying, ‘You came back safely. We were ignorant. We took poison by mistake. Cure us, and give us back our lives!’
“Seeing his sons suffering so much, the father consulted books of prescriptions, and collected good herbs. having a good color, smell and taste. He compounded a medicine by pounding and sieving the herbs, and gave it to them, saying, ‘This is a very good medicine. It has good color, smell and taste. Take it! It will remove the pain at once and you will not suffer any more.’
“The sons who had not lost their right minds saw that this good medicine had a good color and smell, took it at once, and were cured completely. But the sons who had already lost their right minds did not consent to take the medicine given to them, although they rejoiced at seeing their father come home and asked him to cure them, because they were so perverted that they did not believe that this medicine having a good color and smell had a good taste.
“The father thought, ‘These sons are pitiful. They are so poisoned that they are perverted. Although they rejoice at seeing me and ask me to cure them, they do not consent to take this good medicine. Now I will have them take it with an expedient.’
“He said to them, ‘Know this! Now I am old and decrepit. I shall die soon. lam leaving this good medicine here. Take it! Do not be afraid that you will not be cured!’ Having thus advised them, he went to a [remote] country again. Then he sent home a messenger to tell them, ‘Your father has just died.’
“Having heard that their father had passed away from this world, leaving them behind, they felt extremely sorry. They thought, ‘If our father were alive, he would love and protect us. Now he has
deserted us and died in a remote country.’“They felt lonely and helpless because they thought that they were parentless and shelterless. Their constant sadness finally caused them to recover their right minds. They realized that the medicine had a good color, smell and taste. They took it and were completely cured of the poison. On hearing that they had recovered their health, the father returned home, and showed himself to them.