"Then what in the name of goodness are you talking about, may I ask?" he demanded caustically. "If you know nothing of the Straithwaite affair, Max, what other pearl necklace case are you referring to?" Carrados assumed the air of mild deprecation with which he frequently apologized for a blind man venturing to make a discovery. "A philosopher once made the remark----" "Had it anything to do with Mrs Straithwaite's--the Hon. Mrs Straithwaite's--pearl necklace? And let me warn you, Max, that I have read a good deal both of Mill and Spencer at odd times." "It was neither Mill nor Spencer. He had a German name, so I will not mention it. He made the observation, which, of course, we recognize as an obvious commonplace when once it has been expressed, that in order to have an accurate knowledge of what a man will do on any occasion it is only necessary to study a single characteristic action of his." "Utterly impracticable," declared Mr Carlyle. "I therefore knew that when you spoke of a case of exceptional interest to _me_, what you really meant, Louis, was a case of exceptional interest to _you_." Mr Carlyle's sudden thoughtful silence seemed to admit that possibly there might be something in the point. "By applying, almost unconsciously, the same useful rule, I became aware that a mystery connected with a valuable pearl necklace and a beautiful young society belle would appeal the most strongly to your romantic imagination." "Romantic! I, romantic? Thirty-five and a private inquiry agent! You are--positively feverish, Max." "Incurably romantic--or you would have got over it by now: the worst kind." "Max, this may prove a most important and interesting case. Will you be serious and discuss it?" "Jewel cases are rarely either important or interesting. Pearl necklace mysteries, in nine cases out of ten, spring from the miasma of social pretence and vapid competition and only concern people who do not matter in the least. The only attractive thing about them is the name. They are so barren of originality that a criminological Linnæus could classify them with absolute nicety. I'll tell you what, we'll draw up a set of tables giving the solution to every possible pearl necklace case for the next twenty-one years." "We will do any mortal thing you like, Max, if you will allow Parkinson to administer a bromo-seltzer and then enable me to meet the officials of the Direct Insurance without a blush." For three minutes Carrados picked his unerring way among the furniture as he paced the room silently but with irresolution in his face. Twice his hand went to a paper-covered book lying on his desk, and twice he left it untouched. "Have you ever been in the lion-house at feeding-time, Louis?" he demanded abruptly. "In the very remote past, possibly," admitted Mr Carlyle guardedly.