confounding the unusual with the abstruse.  But it is by these deviations from the plane of the ordinary, that reason feels its way, if at all, in its search for the true.  In investigations such as we are now pursuing, it should not be so much asked ‘what has occurred,’ as ’what has occurred that has never occurred before.’  In fact, the facility with which I shall arrive, or have arrived, at the solution of this mystery, is in the direct ratio of its apparent insolubility in the eyes of the police.”

I stared at the speaker in mute astonishment.

“I am now awaiting,” continued he, looking toward the door of our apartment — “I am now awaiting a person who, although perhaps not the perpetrator of these butcheries, must have been in some measure implicated in their perpetration.  Of the worst portion of the crimes committed, it is probable that he is innocent.  I hope that I am right in this supposition; for upon it I build my expectation of reading the entire riddle.  I look for the man here — in this room — every moment.  It is true that he may not arrive; but the probability is that he will.  Should he come, it will be necessary to detain him.  Here are pistols; and we both know how to use them when occasion demands their use.”

I took the pistols, scarcely knowing what I did, or believing what I heard, while Dupin went on, very much as if in a soliloquy.  I have already spoken of his abstract manner at such times.  His discourse was addressed to myself; but his voice, although by no means loud, had that intonation which is commonly employed in speaking to some one at a great distance.  His eyes, vacant in expression, regarded only the wall.

“That the voices heard in contention,” he said, “by the party upon the stairs, were not the voices of the women themselves, was fully proved by the evidence.  This relieves us of all doubt upon the question whether the old lady could have first destroyed the daughter and afterward have committed suicide.  I speak of this point chiefly for the sake of method; for the strength of Madame L’Espanaye would have been utterly unequal to the task of thrusting her daughter’s corpse up the chimney as it was found; and the nature of the wounds upon her own person entirely preclude the idea of self-destruction.  Murder, then, has been committed by some third party; and the voices of this third party were those heard in contention.  Let me now advert - not to the whole testimony respecting these voices — but to what was peculiar in that testimony.  Did you observe any thing peculiar about it?”

I remarked that, while all the witnesses agreed in supposing the gruff voice to be that of a Frenchman, there was much disagreement in regard to the shrill, or, as one individual termed it, the harsh voice.