Āruṇi had a son named Śvetaketu. Once Āruṇi told him - ‘Śvetaketu, you should now live as a brahmacārin. No one in our family has not studied the scriptures and has not been a good brāhmin’.
Śvetaketu went to his teacher’s house at the age of twelve. After studying all the Vedas, he returned home when he was twenty-four, having become very serious and vain, and thinking himself to be a great scholar. (Noticing this) his father said to him - ‘O Śvetaketu, you have now become very serious and vain, and you think you are a great scholar. But did you ask your teacher for that teaching (about Brahman)—
‘—that teaching by which what is never heard becomes heard, what is never thought of becomes thought of, what is never known becomes known?’ (Śvetaketu asked) ‘Sir, what is that teaching?’.
O Somya, it is like this: By knowing a single lump of earth you know all objects made of earth. All changes are mere words, in name only. But earth is the reality.
O Somya, it is like this: By knowing a single lump of gold you know all objects made of gold. All changes are mere words, in name only. But gold is the reality.
O Somya, it is like this: By knowing a single nail-cutter you know all objects made of iron. All changes are mere words, in name only. But iron is the reality. O Somya, this is the teaching I spoke of.
Śvetaketu said - ‘Surely my revered teachers did not know this truth. If they knew it, why should they not have told me? So please explain it to me, sir.’ His father said - ‘Let it be so, my son’.