We have not yet grasped the results which the reason alone canattain to. Problems may be solved in the study which have baffledall those who have sought a solution by the aid of their senses. Tocarry the art， however， to its highest pitch， it is necessary that thereasoner should be able to utilise all the facts which have cometo his knowledge； and this in itself implies， as you will readily see，a possession of all knowledge， which， even in these days of freeeducation and encyclop.dias， is a somewhat rare accomplishment.
It is not so impossible， however， that a man should possess allknowledge which is likely to be useful to him in his work， and thisI have endeavoured in my case to do. If I remember rightly， you onone occasion， in the early days of our friendship， defined my limitsin a very precise fashion.”
“Yes，” I answered， laughing. “It was a singular document.
Philosophy， astronomy， and politics were marked at zero， Iremember. Botany variable， geology profound as regards themud-stains from any region within fifty miles of town， chemistryeccentric， anatomy unsystematic， sensational literature and crimerecords unique， violin-player， boxer， swordsman， lawyer， and selfpoisonerby cocaine and tobacco. Those， I think， were the mainpoints of my analysis.”
Holmes grinned at the last item. “Well，” he said， “I say now， asI said then， that a man should keep his little brain-attic stockedwith all the furniture that he is likely to use， and the rest he canput away in the lumber-room of his library， where he can get itif he wants it. Now， for such a case as the one which has beensubmitted to us to-night， we need certainly to muster all ourresources. Kindly hand me down the letter K of the AmericanEncyclopaedia which stands upon the shelf beside you. Thank you.
Now let us consider the situation and see what may be deducedfrom it. In the first place， we may start with a strong presumptionthat Colonel Openshaw had some very strong reason for leavingAmerica. Men at his time of life do not change all their habits andexchange willingly the charming climate of Florida for the lonelylife of an English provincial town. His extreme love of solitudein England suggests the idea that he was in fear of someone orsomething， so we may assume as a working hypothesis that it wasfear of someone or something which drove him from America. Asto what it was he feared， we can only deduce that by consideringthe formidable letters which were received by himself and hissuccessors. Did you remark the postmarks of those letters？”
“The first was from Pondicherry， the second from Dundee， andthe third from London.”
“From East London. What do you deduce from that？”
“They are all seaports. That the writer was on board of a ship.”
“Excellent. We have already a clue. There can be no doubt thatthe probability—the strong probability—is that the writer wason board of a ship. And now let us consider another point. In thecase of Pondicherry， seven weeks elapsed between the threat andits fulfilment， in Dundee it was only some three or four days. Doesthat suggest anything？”
“A greater distance to travel.”
“But the letter had also a greater distance to come.”
“Then I do not see the point.”
“There is at least a presumption that the vessel in which theman or men are is a sailing-ship. It looks as if they always sendtheir singular warning or token before them when starting upontheir mission. You see how quickly the deed followed the signwhen it came from Dundee. If they had come from Pondicherryin a steamer they would have arrived almost as soon as their letter.
But， as a matter of fact， seven weeks elapsed. I think that thoseseven weeks represented the difference between the mail-boatwhich brought the letter and the sailing vessel which brought thewriter.”
“It is possible.”
“More than that. It is probable. And now you see the deadlyurgency of this new case， and why I urged young Openshaw tocaution. The blow has always fallen at the end of the time which itwould take the senders to travel the distance. But this one comesfrom London， and therefore we cannot count upon delay.”
“Good God！” I cried. “What can it mean， this relentlesspersecution？”
“The papers which Openshaw carried are obviously of vitalimportance to the person or persons in the sailing-ship. I thinkthat it is quite clear that there must be more than one of them. Asingle man could not have carried out two deaths in such a way asto deceive a coroner’s jury. There must have been several in it， andthey must have been men of resource and determination. Theirpapers they mean to have， be the holder of them who it may. Inthis way you see K. K. K. ceases to be the initials of an individualand becomes the badge of a society.”
“But of what society？”
“Have you never—” said Sherlock Holmes， bending forward andsinking his voice—“have you never heard of the Ku Klux Klan？”
“I never have.”
Holmes turned over the leaves of the book upon his knee. “Hereit is，” said he presently：