“The only unofficial consulting detective,” he answered. “I am the last and highest court of appeal in detection. When Gregson 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.”

“Yes, indeed,” said I, cordially. “I was never so struck by anything in my life. I even embodied it in a small brochure with the somewhat fantastic title of ‘A Study in Scarlet.’ ”

He shook his head sadly. “I glanced over it,” said he. “Honestly, I cannot congratulate you upon it. Detection is, or ought to be, an exact science, and should be treated in the same cold and unemotional manner. You have attempted to tinge it with romanticism, which produces much the same effect as if you worked a love-story or an elopement into the fifth proposition of Euclid.”