ready-handed criminal agent, as it was possible to conceive. In his
singular character the dual nature alternately presented itself, and
his extreme exactness and astuteness represented, as I have often
thought, the reaction against the poetic and contemplative mood which
occasionally predominated in him. The swing of his nature took him from
extreme languor to devouring energy; and, as I knew well, he was never
so truly formidable as when, for days on end, he had been lounging in
his arm-chair amid his improvisations and his black-letter editions.
Then it was that the lust of the chase would suddenly come upon him,
and that his brilliant reasoning power would rise to the level of
intuition, until those who were unacquainted with his methods would
look askance at him as on a man whose knowledge was not that of other
mortals. When I saw him that afternoon so enwrapped in the music at St.
James's Hall I felt that an evil time might be coming upon those whom
he had set himself to hunt down.

"You want to go home, no doubt, doctor," he remarked, as we emerged.

"Yes, it would be as well."

"And I have some business to do which will take some hours. This
business at Coburg Square is serious."

"Why serious?"

"A considerable crime is in contemplation. I have every reason to
believe that we shall be in time to stop it. But to-day being Saturday
rather complicates matters. I shall want your help to-night."

"At what time?"

"Ten will be early enough."

"I shall be at Baker Street at ten."

"Very well. And, I say, doctor, there may be some little danger, so
kindly put your army revolver in your pocket." He waved his hand,
turned on his heel, and disappeared in an instant among the crowd.

I trust that I am not more dense than my neighbors, but I was always
oppressed with a sense of my own stupidity in my dealings with Sherlock
Holmes. Here I had heard what he had heard, I had seen what he had
seen, and yet from his words it was evident that he saw clearly not
only what had happened, but what was about to happen, while to me the
whole business was still confused and grotesque. As I drove home to my
house in Kensington I thought it all over, from the extraordinary story
of the red-headed copier of the "Encyclopaedia" down to the visit to
Saxe-Coburg Square, and the ominous words with which he had parted from
me. What was this nocturnal expedition, and why should I go on? Where
were we going, and what were we to do? I