Quote 10
He was, I take it, the most perfect reasoning and observing machine that the world has seen, but as a lover he would have placed himself in a false position. He never spoke of the softer passions, save with a gibe and a sneer. They were admirable things for the observer – excellent for drawing the veil from men's motives and actions. But for the trained reasoner to admit such intrusions into his own delicate and finely adjusted temperament was to introduce a distracting factor which might throw a doubt upon all his mental results (Scandal.1.1).
The equation here seems to be Holmes = rational and Holmes = passionless. So rational = passionless. To be a good detective, you can't feel the "softer passions" for fear of distracting yourself from correct "mental results." What does this have to do with women? This is Watson's explanation for why Holmes seems to avoid love relationships with the ladies. Holmes often helps women as clients, but anything more would be "a false position." With the notable exception of Irene Adler (see our "Characters"), Holmes's interactions with women seem really hierarchical: he's the brainy guy who's going to solve the emotional little lady's problems. But once her problems are solved, it's back to Baker Street with Watson.
Quote 11
I walked down to the station with them, and then wandered through the streets of the little town, finally returning to the hotel, where I lay upon the sofa and tried to interest myself in a yellow-backed novel. The puny plot of the story was so thin, however, when compared to the deep mystery through which we were groping, and I found my attention wander so continually from the action to the fact, that I at last flung it across the room and gave myself up entirely to a consideration of the events of the day (Valley.106).
During "The Boscombe Valley Mystery," Watson is left to his own devices for a bit, so he turns to a novel for a good time. A "yellow-backed novel" is a cheap, generally melodramatic book often sold in railway stations in days of yore – kind of like the Patricia Cornwell and Kathy Reichs books we find in airport bookstores now. There's a neat bit of self-marketing here: Watson's disgusted with the plot of the novel when compared to the depth of the mystery he's right in the middle of. But that mystery is, again, a piece of fiction invented and sold by one Sir Arthur Conan Doyle. So there's a lot of nod-nod-wink-wink self-referential joking going on in this passage. Does all of Conan Doyle's poking at fiction make his Holmes stories seem more realistic to you?
Quote 12
The story has, I believe, been told more than once in the newspapers, but, like all such narratives, its effect is much less striking when set forth en bloc in a single half-column of print than when the facts slowly evolve before your own eyes, and the mystery clears gradually away as each new discovery furnishes a step which leads on to the complete truth (Thumb.1).
Ah ha! Now here we get a neat argument from Watson about why it's important to include color and intrigue in a story. A newspaper article gives you all the facts at once, without suspense. But the process of the slow reveal is essential, says Watson, to create a "striking" effect for the reader. In other words, what makes Watson's narration memorable is that he chooses to withhold information from us until he's good and ready to let us in on the secret. That's some good suspense!