Sherlock: It has its costs.

Watson: What does?

Sherlock: Learning to see the puzzle in everything. They're everywhere. Once you start looking, it's impossible to stop. It just so happens that people, and all the deceits and delusions that inform everything they do, tend to be the most fascinating puzzles of all. Of course, they don't always appreciate being seen as such.

Watson: Seems like a lonely way to live.

Sherlock: As I said, it has its costs.