Here, then, was my problem: given an envelope with the Basingstoke postmark, to find in what part of Europe, Asia, Africa, or America the writer of it might be discovered.

It opened up a fine field for speculation.
When I set out to face this broad puzzle, my first idea was: "I must ask Hilda." In all circumstances of difficulty, I had grown accustomed to submitting my doubts and surmises to her acute intelligence; and her instinct almost always supplied the right solution.

But now Hilda was gone; it was Hilda herself I wished to track through the labyrinth of the world.

I could expect no assistance in tracking her from Hilda.
"Let me think," I said to myself, over a reflective pipe, with feet poised on the fender.

"How would Hilda herself have approached this problem?
Imagine I'm Hilda.