He smiled at my vehemence. "Perhaps you are right, Wat– son," he said. "I suppose that its influence is physically a bad one. I find it, however, so transcendently stimulating and clarify– ing to the mind that its secondary action is a matter of small moment."

"But consider!" I said earnestly. "Count the cost! Your brain may, as you say, be roused and excited, but it is a pathological and morbid process which involves increased tissue-change and may at least leave a permanent weakness. You know, too, what a black reaction comes upon you. Surely the game is hardly worth the candle. Why should you, for a mere passing pleasure, risk the loss of those great powers with which you have been endowed? Remember that I speak not only as one comrade to another but as a medical man to one for whose constitution he is to some extent answerable."

He did not seem offended. On the contrary, he put his finger– tips together, and leaned his elbows on the arms of his chair, like one who has a relish for conversation.

"My mind," he said, "rebels at stagnation. Give me prob– lems, give me work, give me the most abstruse cryptogram, or the most intricate analysis, and I am in my own proper atmo– sphere. I can dispense then with artificial stimulants. But I abhor the dull routine of existence. I crave for mental exaltation. That is why I have chosen my own particular profession, or rather created it, for I am the only one in the world."

"The only unofficial detective?" I said, raising my eyebrows.

"The only unofficial consulting detective," he answered. "I am the last and highest court of appeal in detection. When Greg– son, or Lestrade, or Athelney Jones are out of their depths – which, by the way, is their normal state – the matter is laid before me. I examine the data, as an expert, and pronounce a specialist's opinion. I claim no credit in such cases. My name figures in no newspaper. The work itself, the pleasure of finding a field for my peculiar powers, is my highest reward. But you have yourself had some experience of my methods of work in the Jefferson Hope case."