"In my knowledge of persons," he replied. "In my knowledge of their fears, their hopes, and their individual concerns. If I were twenty years younger"--here he stole a glance at me in the mirror which made me bridle; did he think I was only twenty years younger than himself?--"I would," he went on, "make myself so acquainted with every man, woman, and child there, that--" Here he drew himself up with a jerk. "But the day for that is passed," said he. "I am too old and too crippled to succeed in such an undertaking. Having been there once, I am a marked man. My very walk betrays me. He whose good fortune it will be to get at the bottom of these people's hearts must awaken no suspicions as to his connection with the police. Indeed, I do not think that any man can succeed in doing this now." I started. This was a frank showing of his hand at least. No man! It was then a woman's aid he was after. I laughed as I thought of it. I had not thought him either so presumptuous or so appreciative of talents of a character so directly in line with his own. "Don't you agree with me, madam?" I did agree with him; but I had a character of great dignity to maintain, so I simply surveyed him with an air of well-tempered severity. "I do not know of any woman who would undertake such a task," I calmly observed. "No?" he smiled with that air of forbearance which is so exasperating to me. "Well, perhaps there isn't any such woman to be found. It would take one of very uncommon characteristics, I own." "Pish!" I cried. "Not so very!" "Indeed, I think you have not fully taken in the case," he urged in quiet superiority. "The people there are of the higher order of country folk. Many of them are of extreme refinement. One family"--here his tone changed a trifle--"is poor enough and cultivated enough to interest even such a woman as yourself." "Indeed!" I ejaculated, with just a touch of my father's hauteur to hide the stir of curiosity his words naturally evoked. "It is in some such home," he continued with an ease that should have warned me he had started on this pursuit with a quiet determination to win, "that the clue will be found to the mystery we are considering. Yes, you may well look startled, but that conclusion is the one thing I brought away with me from--X., let us say. I regard it as one of some moment. What do you think of it?" "Well," I admitted, "it makes me feel like recalling that _pish_ I uttered a few minutes ago. It would take a woman of uncommon characteristics to assist you in this matter." "I am glad we have got that far," said he. "A lady," I went on. "Most assuredly a lady." I paused. Sometimes discreet silence is more sarcastic than speech. "Well, what lady would lend herself to this scheme?" I demanded at last. The tap, tap of his fingers on the rim of his glasses was my only answer. "I do not know of any," said I.