'And as, my dear, by one pair of nail-scissors all that is made of iron (kârshnâyasam) is known, the difference being only a name, arising from speech, but the truth being that all is iron,—thus, my dear, is that instruction.'

In plain words: In the same way, if you know one pair of iron nail clippers, you know everything made of iron, because all of it is really iron. The father says the teaching he means works like this: knowing the one source lets you know everything.