魔鬼之足（20）

 “You know,” I answered with some emotion, for I have never seen so much of Holmes's heart before, “that it is my greatest joy and privilege to help you.”

He relapsed at once into the half-humorous, half-cynical vein which was his habitual attitude to those about him. “It would be superfluous to drive us mad, my dear Watson,” said he. “A candid observer would certainly declare that we were so already before we embarked upon so wild an experiment. I confess that I never imagined that the effect could be so sudden and so severe.” He dashed into the cottage, and, reappearing with the burning lamp held at full arm's length, he threw it among a bank of brambles. “We must give the room a little time to clear. I take it, Watson, that you have no longer a shadow of a doubt as to how these tragedies were produced?”

“None whatever.”

“But the cause remains as obscure as before. Come into the arbour here and let us discuss it together. That villainous stuff seems still to linger round my throat. I think we must admit that all the evidence points to this man, Mortimer Tregennis, having been the criminal in the first tragedy, though he was the victim in the second one. We must remember, in the first place, that there is some story of a family quarrel, followed by a reconciliation. How bitter that quarrel may have been, or how hollow the reconciliation we cannot tell. When I think of Mortimer Tregennis, with the foxy face and the small shrewd, beady eyes behind the spectacles, he is not a man whom I should judge to be of a particularly forgiving disposition. Well, in the next place, you will remember that this idea of someone moving in the garden, which took our attention for a moment from the real cause of the tragedy, emanated from him. He had a motive in misleading us. Finally, if he did not throw the substance into the fire at the moment of leaving the room, who did do so? The affair happened immediately after his departure. Had anyone else come in, the family would certainly have risen from the table. Besides, in peaceful Cornwall, visitors did not arrive after ten o'clock at night. We may take it, then, that all the evidence points to Mortimer Tregennis as the culprit.”