In the Parable of the Physician’s Sons, the physician is the Buddha and the sons represent all living beings. The gist of the parable is that living beings cannot understand how much they owe to the Buddha as long as he abides in this world, but they conceive the desire to seek his teachings earnestly when he becomes extinct. For this reason, he temporarily enters nirvana through his tactful means.

The Buddha teaches us several important lessons in this parable. The first significant point is that the sons drink poisonous medicines while their father is away in a distant country. The poisonous medicines are illusions produced by the five desires. If people come in contact with the Buddha’s teachings daily, they will not suffer from these five desires disturbing their minds. However, when they avoid the Buddha’s teachings, they are apt to become obsessed by the five desires.

The next important point is that all the sons who drank the poison, even those who have lost their senses, to say nothing of the others who are still in their right minds, are delighted on seeing their father return home. The parable thus shows that even a madman can tell his father from other people. In the same way, even those with illusions who have lost their senses, for example, even a thoroughgoing materialist who boasts, “I don’t believe in God or the Buddha,” in the depths of his mind feels an unrest and loneliness that he cannot quite satisfy by material things. He seeks mental calm and satisfaction, though he is unaware of it. Therefore, if he encounters a teaching giving him spiritual peace and enlightenment, he is sure to be delighted with it. This is the same the sons who have lost their senses being glad to see their father approaching in the distance.