Now consider this explanation: I give someone two boxes containing various things, and say, “The object which both these boxes have in common is called a toasting fork”. The person I give this explanation to has to sort out the objects in the two boxes until he finds the one they have in common, and thereby we may say, he arrives at the ostensive explanation. Or, this explanation: “In these two pictures you see patches of many colours; the one colour which you find in both is called ‘mauve’”. ‒ ‒ In this case it makes a clear sense to say, “If he has seen (or found) what is in common between these two pictures, he can now bring me a mauve object.”