He is very cunning.

Yes, my pure reason pointed to him; but I required tangible proof so that my eyes could see him as my pure reason saw him." "What do you mean by your pure reason ?" "That power of one's mind which admits of no disturbing elements to a conclusion.

The day following the incident of 'the inexplicable gallery,' I felt myself losing control of it.

I had allowed myself to be diverted by fallacious evidence; but I recovered and again took hold of the right end.

I satisfied myself that the murderer could not have left the gallery, either naturally or supernaturally.