The Kaṭhopaniṣad was written well after the Bhagavad Gītā and is one of the most beautiful of the Upaniṣads. It tells the story of Nāciketa in the intermediate point between life and death - he receives a lecture on life and human society from Kṛṣṇa, and then finds that his soulmate is the Goddess Gāyatrī, the Goddess of Music and the author of the Vedas, and that She has made the traditional Hindu marriage vow of eternal friendship in marriage, and indicates that She will chase him in every lifetime. The book also discusses the concept of justice and its implementation, as directed by Kṛṣṇa.