"All criminals should be caught. That they are not is a strong argument against your detective; for every criminal, we may say is actuated by necessity, and therein lies the possibility of his defeat. For example: You may claim that the expert burglar lays his plans in advance, and that the crime being premeditated he should be able to make such careful pre-arrangements that he could avoid leaving tell-tale marks behind him. This, however, is rarely the case, for this reason: the unexpected often, if not always, happens, and for that he has not prepared. In a moment he sees prison ahead of him, and his fear steals away his caution, so that, as we have seen, he does leave a clue behind him." "But when you say the unexpected happens, you admit the possibility for that to occur which could not have been premised, and therefore could not have been guarded against." "That is true as the case stands. But remove the necessity which actuates our criminal, and make of him simply a scientific man pursuing crime as an art! In the first place, we get an individual who will prepare for more accidents, and secondly, would know how best to meet emergencies which occur during the commission of his crime. For example: if you will pardon the conceit, were I to attempt a crime I should be able to avoid detection." "I should think that from your inexperience as a criminal you would be run to earth--well, about as quickly as this man Pettingill. This was his first crime you know." "Would you be willing to make a wager to that effect?" This last remark fairly startled Mr. Barnes, who instantly understood the meaning, which, however, at first escaped the other listener. He waited eagerly for the reply. "I don't grasp the idea. Make a wager about what?" "You said that were I to commit a crime I should be captured about as quickly as Pettingill. If you wish, I will wager that I can commit a crime which will be as much talked of as his, and that I will not be captured, or rather I should say convicted. I would not bet against arrest; for, as we have seen in this very case, the innocent are sometimes incarcerated. Therefore I stipulate for conviction." "Do I understand you to seriously offer to commit a crime merely to decide a wager? You astound me!" "No more perhaps than Pettingill has surprised his friends. But don't be alarmed; I shall assume all responsibility. Besides, remember it is not crime that is scowled upon in this century, but detection. I wager with you against that. Come, what do you say; shall it be a thousand dollars? I want a little excitement!" "Well, you shall have it. At least you shall have the excitement of paying the thousand dollars to me; for though I think you are not really intending to become a criminal, in either event I may as well profit by your offer." "What do you mean by 'in either event'?"