“I know not,” continued Dupin, “what impression I may have made, so far, upon your own understanding; but I do not hesitate to say that legitimate deductions even from this portion of the testimony—the portion respecting the gruff and shrill voices—are in themselves sufficient to engender a suspicion which should give direction to all farther progress in the investigation of the mystery. I said ‘legitimate deductions;’ but my meaning is not thus fully expressed. I designed to imply that the deductions are the _sole_ proper ones, and that the suspicion arises _inevitably_ from them as the single result. What the suspicion is, however, I will not say just yet. I merely wish you to bear in mind that, with myself, it was sufficiently forcible to give a definite form—a certain tendency—to my inquiries in the chamber. “Let us now transport ourselves, in fancy, to this chamber. What shall we first seek here? The means of egress employed by the murderers. It is not too much to say that neither of us believe in præternatural events. Madame and Mademoiselle L’Espanaye were not destroyed by spirits. The doers of the deed were material, and escaped materially. Then how? Fortunately, there is but one mode of reasoning upon the point, and that mode _must_ lead us to a definite decision. Let us examine, each by each, the possible means of egress. It is clear that the assassins were in the room where Mademoiselle L’Espanaye was found, or at least in the room adjoining, when the party ascended the stairs. It is then only from these two apartments that we have to seek issues. The police have laid bare the floors, the ceilings, and the masonry of the walls, in every direction. No _secret_ issues could have escaped their vigilance. But, not trusting to _their_ eyes, I examined with my own. There were, then, no secret issues. Both doors leading from the rooms into the passage were securely locked, with the keys inside. Let us turn to the chimneys. These, although of ordinary width for some eight or ten feet above the hearths, will not admit, throughout their extent, the body of a large cat. The impossibility of egress, by means already stated, being thus absolute, we are reduced to the windows. Through those of the front room no one could have escaped without notice from the crowd in the street. The murderers _must_ have passed, then, through those of the back room. Now, brought to this conclusion in so unequivocal a manner as we are, it is not our part, as reasoners, to reject it on account of apparent impossibilities. It is only left for us to prove that these apparent ‘impossibilities’ are, in reality, not such.