I did not doubt it. I believed every word that dropped from Jack's lips, and it set me thinking. The extraordinary turn which his disclosure had given to the Mystery opened up so many channels of conjecture, some of which would assuredly be misleading and likely to throw a man off the track, that I recognized the imperative necessity of proceeding with the utmost care. To avoid falling into a pit of confusion, system was no less necessary; the threads must be disentangled; Jack's statement and John Fordham's Confession must be studied and compared and discrepancies accounted for, not by the light of any extraordinary agency, but by that of common sense; and when all this was done the principal difficulties had yet to be encountered. There were many doors in the Mystery, two or three of which were now either quite or partially open; the others were locked, and it was for me to find the keys. Partly for John Fordham's sake, and chiefly for the sake of Miss Cameron, I was elated by the discovery that it was not he who had killed his half-brother Louis. It gave me the greatest pleasure to think of the exquisite feeling of relief she would experience when I supplied her with proof of his innocence--sufficient for her and for me, but not sufficient, perhaps, in a legal sense. Considering the feelings I entertained for Ellen Cameron, it may appear strange that I should have become so zealous in the cause of the man who had supplanted me, but there is nothing in the world so enthralling as the gradual unfolding of a mystery such as this; there is no task so absorbing as that of following it up step by step, and of at length piercing the darkness which at first seemed impenetrable. There are higher callings than mine, but I doubt if there are any more interesting; and if you think it is one which does not demand fine powers of reasoning, as well as the exercise of physical courage, you are greatly mistaken. As for the hold it has upon the public, there is no question about that. It is easily to be accounted for. If a simple puzzle which is sold in the streets for a penny will interest thousands of 'people, how much more so will a puzzle so intricate and mysterious upon the unraveling of which the lives and happiness of human beings depend? You may run us down as much as you like (I have just been reading something of the kind), but you can't do without us, and will never be able to; and without us, many and many a wrong would never be righted. And after all, what are your finest lawyers, and judges, and Lord Chief Justices but a superior kind of detective? There are black sheep among us, and there are black sheep among them. There are black sheep everywhere. So, having had my say, I will go on with my story.