We have not yet grasped the results which the reason alone can attain to. Problems may be solved in the study which have baffled all those who have sought a solution by the aid of their senses. To carry the art, however, to its highest pitch, it is necessary that the reasoner should be able to utilise all the facts which have come to his knowledge; and this in itself implies, as you will readily see, a possession of all knowledge, which, even in these days of free education and encyclopaedias, is a somewhat rare accomplishment. It is not so impossible, however, that a man should possess all knowledge which is likely to be useful to him in his work, and this I have endeavoured in my case to do. If I remember rightly, you on one occasion, in the early days of our friendship, defined my limits in a very precise fashion."
"Yes," I answered, laughing. "It was a singular document. Philosophy, astronomy, and politics were marked at zero, I remember. Botany variable, geology profound as regards the mud-stains from any region within fifty miles of town, chemistry eccentric, anatomy unsystematic, sensational literature and crime records unique, violin-player, boxer, swordsman, lawyer, and self-poisoner by cocaine and tobacco. Those, I think, were the main points of my analysis."
Holmes grinned at the last item. "Well," he said, "I say now, as I said then, that a man should keep his little brain-attic stocked with all the furniture that he is likely to use, and the rest he can put away in the lumber-room of his library, where he can get it if he wants it. Now, for such a case as the one which has been submitted to us to-night, we need certainly to muster all our resources. Kindly hand me down the letter K of the 'American Encyclopaedia' which stands upon the shelf beside you. Thank you. Now let us consider the situation and see what may be deduced from it. In the first place, we may start with a strong presumption that Colonel Openshaw had some very strong reason for leaving America. Men at his time of life do not change all their habits and exchange willingly the charming climate of Florida for the lonely life of an English provincial town. His extreme love of solitude in England suggests the idea that he was in fear of someone or something, so we may assume as a working hypothesis that it was fear of someone or something which drove him from America. As to what it was he feared, we can only deduce that by considering the formidable letters which were received by himself and his successors. Did you remark the postmarks of those letters?"
"The first was from Pondicherry, the second from Dundee, and the 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 that the probability--the strong probability--is that the writer was on board of a ship. And now let us consider another point. In the case of Pondicherry, seven weeks elapsed between the threat and its fulfilment, in Dundee it was only some three or four days. Does that 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 the man or men are is a sailing-ship. It looks as if they always send their singular warning or token before them when starting upon their mission. You see how quickly the deed followed the sign when it came from Dundee. If they had come from Pondicherry in a steamer they would have arrived almost as soon as their letter. But, as a matter of fact, seven weeks elapsed. I think that those seven weeks represented the difference between the mail-boat which brought the letter and the sailing vessel which brought the writer."
"It is possible."
"More than that. It is probable. And now you see the deadly urgency of this new case, and why I urged young Openshaw to caution. The blow has always fallen at the end of the time which it would take the senders to travel the distance.