Lichtenberg said somewhere, “I used to know people of great scholarship, in whose head the most important propositions were folded up in excellent order. But I don’t know what occurred there, whether the ideas were all mannikins or all little women--there were no results. In one corner of the head, these gentlemen put away saltpeter, in another sulphur, in a third charcoal, but these did not combine into gunpowder. Then again, there are people in whose heads everything seeks out and finds everything else, everything pairs off with everything else, and arranges itself variously.” What Lichtenberg is trying to do is to indicate that the cause of the happy condition of the last-named friends is imagination. That imagination is influential, is certain, but it is equally certain that the human understanding is so different with different people as to permit such phenomena as Lichtenberg describes. I do not want to discuss the quantity of understanding. I shall deal, this time, with its quality, by means of which the variety of its uses may be explained. It would be a mistake to think of the understanding as capable of assuming different forms. If it were it would be possible to construct from the concept understanding a group of different powers whose common quality would come to us off-hand. But with regard to understanding we may speak only of more or less and we must think of the difference in effect in terms only of the difference of the forms of its application. We see the effects of the understanding alone, not the understanding itself, and however various a burning city, cast iron, a burn, and steaming water may be, we recognize that in spite of the difference of effect, the same fire has brought about all these results. The difference in the uses of the understanding, therefore, lies in the manner of its application. Hence these applications will help us, when we know them, to judge the value of what they offer us. The first question that arises when we are dealing with an important witness who has made observations and inferences, is this: “How intelligent is he? and what use does he make of his intelligence? That is, What are his processes of reasoning?” I heard, from an old diplomat, whose historic name is as significant as his experience, that he made use of a specific means to discover what kind of mind a person had. He used to tell his subjects the following story: “A gentleman, carrying a small peculiarly-formed casket, entered a steam car, where an obtrusive commercial traveler asked him at once what was contained in the casket. ‘My Mungo is inside!’ ‘Mungo? What is that?’ ‘Well, you know that I suffer from delirium tremens, and when I see the frightful images and figures, I let my Mungo out and he eats them up.’ ‘But, sir, these images and figures do not really exist.’ ‘Of course they don’t really exist, but my Mungo doesn’t really exist, either, so it’s all right!’”