O Nachiketas, this is thy fire that leads to heaven, which thou hast chosen as thy second boon. People will call this fire after thy name. Ask the third boon, Nachiketas.
Fire is regarded as "the foundation of all the worlds," because it is the revealer of creation. If there were no fire or light, no manifested form would be visible. We read in the Semitic Scriptures, "In the beginning the Lord said, 'Let there be light."' Therefore, that which stands in the external universe as one of the purest symbols of the Divine, also dwells in subtle form in the heart of every living being as the vital energy, the life-force or cause of existence.
Yama now tells Nachiketas how, by performing sacrifice with the three-fold knowledge, he may transcend grief and death and reach heaven. The three-fold knowledge referred to is regarding the preparation of the altar and fire. Nachiketas being eager to learn, listened with wholehearted attention and was able to repeat all that was told him. This so pleased Yama that he granted him the extra boon of naming the fire-sacrifice after him and gave him a garland set with precious stones.
Verses XVI-XVIII are regarded by many as an interpolation, which would account for certain obscurities and repetitions in them.