In order to understand the effect these culpable confessions produced upon me, my readers ought to know what it is to love a science of which you seek to solve the mysteries. Far from feeling repugnance or even disgust at this man with whom justice would have one day an account to settle, I admired, I was stunned! The finesse and perfection of his tricks made me forget their blameworthy application. At length my Greek left me, and so soon as he was gone the remembrance of his confessions sent the blood to my cheeks. I was as ashamed of myself as if I had been his accomplice. I even reproached myself severely for the admiration I could not restrain, and the compliments it extorted from me. In some measure to compound with my conscience, I ordered my door to be closed against this man; but it was an unnecessary precaution--I never heard of him again. Strangely enough, in consequence of my meeting with D----, and the revelations he had made me, I was enabled, at a later period, to render a service to society by unmasking a piece of swindling which the most skillful experts could not detect. In 1849, M. B----, a magistrate belonging to the police office of the Seine, begged me to examine and verify one hundred and fifty packs of cards, seized in the possession of a man whose antecedents were far from being as unblemished as his cards. The latter, indeed, were perfectly white, and this peculiarity had hitherto foiled the most minute investigation. It was impossible for the most practised eye to detect the least alteration or the slightest mark, and they all seemed very respectable packs of cards. I consented to examine the cards, as I hoped to detect a manœuvre which must be clever as it was so carefully concealed. I could only do so after my performance was over, and so each night, before going to bed, I sat down with a bright lamp, and remained at my task till sleep or want of success routed me from my post. Thus I spent nearly a fortnight, examining, both with my eyes and a strong magnifying-glass, the form and imperceptible varieties in the cards composing the one hundred and fifty packs. I could detect nothing, and, weary of the job, I began to agree in the opinion of the previous experts. “I am sure there is nothing the matter with these cards,” I said one night, angrily, as I threw them across the table. Suddenly I fancied I noticed a pale spot on the glistening back of these cards, and near one of the corners. I stepped forward, and it disappeared, but, strangely enough, it reappeared as I fell back. “What a magnificent dodge!” I exclaimed, in my enthusiasm. “I have it: that is a distinguishing mark.” And following a certain principle which D---- had explained to me, I assured myself that all the cards possessed a mark, which, according to its position, indicated the value and color.