In Genesis 4:22, 'Tubal-Cain, an instructor of every artificer in brass and iron,' as in Genesis 4:22, signifies the doctrine of natural good and truth. Tubal-Cain is called an instructor of every artificer, and not a father, like Jabal and Jubal, because celestial and spiritual, or internal things, did not exist before. This is why the term 'father' is applied in the case of Jabal and Jubal, the first existence of these internal things. As natural or external things existed before, but were now applied to internal things, Tubal-Cain is not called a father, but an instructor of the artificer. (Arcana Coelestia 421)

421. Verse 22 And Zillah also, she gave birth to Tubal-cain, teacher of every craftsman in bronze and iron. And Tubal-cain's sister was Naamah. 'Zillah', as has been stated, means the mother of the natural features of the new Church. 'Tubal-cain, a teacher of every craftsman in bronze and iron' means the doctrine of natural good and truth; 'bronze' means natural good, 'iron' natural truth. 'Tubal-cain's sister was Naamah' means another Church or doctrine of natural good and truth, which though similar was not an integral part of that Church.