The Hound of the Baskervilles

EXCERPT: 

"No mention of that local hunt, Watson," said Holmes with a mischievous smile, "but a country doctor, as you very astutely observed.  I think that I am fairly justified in my inferences. As to the adjectives, I said, if I remember right, amiable, unambitious, and absent-minded.  It is my experience that it is only an amiable man in this world who receives testimonials, only an unambitious one who abandons a London career for the country, and only an absent-minded one who leaves his stick and not his visiting-card after waiting an hour in your room."
 
"And the dog?"
 
"Has been in the habit of carrying this stick behind his master. Being a heavy stick the dog has held it tightly by the middle, and the marks of his teeth are very plainly visible.  The dog's jaw, as shown in the space between these marks, is too broad in my opinion for a terrier and not broad enough for a mastiff.  It may have been--yes, by Jove, it is a curly-haired spaniel."
 
He had risen and paced the room as he spoke.  Now he halted in the recess of the window.  There was such a ring of conviction in his voice that I glanced up in surprise.
 
"My dear fellow, how can you possibly be so sure of that?"