In plain words
In the Kaṭhopaniṣad, among the three boons Nachiketa asked of Yama, the question of death shone forth as the principal one. 'Does a person, once dead, continue to exist? Some tell me he exists, and others tell me he does not, each according to their own opinion. Which of these is the truth? Tell me this secret' — so Nachiketa insisted. Without giving him an answer, Yama said, 'My child, Nachiketa! That secret is impenetrable. The scriptures on it are exceedingly subtle. Even the gods find it impossible to explain; yet such is the boon you have asked for. Why do you need such a thing? You are only a boy. There are so many pleasures in this world that you deserve to enjoy. I shall grant you great wealth and riches — take them and enjoy every comfort. Whatever worldly enjoyments and fortunes you desire, however many, I shall give you; only ask for them' — so he said. To this Nachiketa replied, 'O Dharmarāja! However great the riches, however many the enjoyments, none of them can exist in this creation without their bond to you — is that not so? All these pleasures, being mingled with death, bring only temporary relief — what use have I for them? Grant me instead the very boon I have asked for.' So he entreated.
In the Mahābhārata, to the question 'What is the most wondrous thing in this world?', Dharmarāja gave the answer: 'Every day we see death around us, yet we never think or imagine that we ourselves will die. What could be more wondrous than this?' In just the same way, Yājñavalkya, having resolved to renounce the world, called his two wives Kātyāyanī and Maitreyī and sought to divide all his movable and immovable wealth between them. But his first wife Maitreyī, a woman of great wisdom, looked at her husband with a smile playing on her lips and said: 'My lord! Can this worldly wealth free me from the grip of death and make me immortal? If you give your guarantee that it can, I shall accept it without fail, and bow my head to it.' So she questioned him. To this —