An ugly light shone in the duke’s eyes.  “I do not want to seem importunate,” he said, “but—­I would do very much for the man who furthered my marriage with Miss Randolph, and you would find the alliance of our families of great advantage.  I am a hot-blooded fellow, but I’m not such a bad lot.  I cannot help being wounded, though, by your niece’s indifference, and in jealousy of a rival I might do things that otherwise would not enter my head.  This is—­eh—­not a threat—­but it is a family trait—­the Scorpas stop at nothing once their hearts are aflame!  Think it over, my friend, before you decide not to help me.”

He sighed deeply and then, as though turning his attention to the first trivial thought that came to mind, he said casually:  “By the way, I have been reading lately an extremely interesting book on celebrated criminal cases, and I was particularly impressed by the way in which circumstantial evidence can be built up out of harmless trifles.  Since reading it I have been rather amusing myself by constructing hypothetical cases.  For instance”—­Scorpa pursed his lips and lowered his eyes, as though trying to invent a fanciful story—­“take a transaction such as your letting me have that picture.  One could build a very stirring case upon that!”

“Yes?” encouraged the prince.  “How do you mean?”

“Well, to begin, we would send word to the government that your Raphael Madonna had been sold out of the country.”

“I don’t think that a good beginning, because it is easy enough to prove it is in your palace.”

“Ah, of course.  But for the amusement of the argument we will say that I want to do you an injury and so smuggle it out of the country!  Then when I am questioned, I deny all knowledge of it.  Yes, I would have you there!  It would be quite feasible, because no one saw the picture change hands, and your notes to me—­the only proof of the transfer—­could easily be destroyed.  You see?  This really grows interesting!  Then comes all the cumulative evidence of the type I was speaking about; for instance:  After the supposed sale of the picture, you indulge in unwonted expenditures—­of course, it is easy to say that they are those of the American heiress stopping with you”—­he paused, in apparent thoughtfulness—­“but when, in addition, an enemy buys in Paris a pair of earrings, matchless emeralds, that are recognized as having been worn——­”

“Dio mio! My wife’s emeralds!” Sansevero was startled into exclaiming.  Then suddenly he blazed out:  “What do you mean by your story?  If you have anything to say, say it so I can follow you.”

From the gross lips of the duke his apology fell like drops of thickest oil:  “I regret you take my pleasantry so ill, and I ask your pardon as many times as you require, my friend!  It happened by chance that I saw a pair of emeralds in Paris that were duplicates of the magnificent gems I have often admired when the princess wore them, and the jeweler told me that they had been sold at a sacrifice by a noble lady in urgent need of money.  The curious coincidence came to my mind in illustration of the problems I was talking of.  Further than that I meant nothing—­except that I was serious in what I said about repaying the man who should bring about my marriage.”