How Do I Know What I Think Until I See What I Say?

I'm reading The Pale Blue Eye by Louis Bayard. I haven't read his other books, so this is my first experience of him. I'm enjoying it so far (I did a masters in Victorian English, so my taste in reading is sometimes not the taste of the general public), but I am a bit annoyed by one of his ... well, I'll call it a cheat. The story is in first person, told by a cranky old constable who meets a young Edgar Allen Poe and helps solve a murder at West Point. So the constable is educating young Poe and we see some things that foreshadow Poe's future development and career as a writer. All this is fine. What is not fine is that the constable apparently has magic powers, because he somehow comes across or knows clues that we don't see him discover. HERE BE SPOILERS: So the constable is educating young Poe and we see some things that foreshadow Poe's future development and career as a writer. All this is fine. What is not fine is that the constable apparently has ma