'What is that instruction, Sir?' he asked. The father replied: 'My dear, as by one clod of clay all that is made of clay is known, the difference being only a name, arising from speech, but the truth being that all is clay;

In plain words: Shvetaketu asks what that teaching is. His father explains: if you know one lump of clay, you know everything made of clay. Pots and bowls have different names, but they are all really just clay.