"In notes to Camberwell post office."

"Did you ever trouble to see who called for them?"

"No."

The inspector looked surprised and a little shocked. "Why not?"

"Because I always keep faith. I had promised when he first wrote
that I would not try to trace him."

"You think there is someone behind him?"

"I know there is."

"This professor that I've heard you mention?"

"Exactly!"

Inspector MacDonald smiled, and his eyelid quivered as he glanced
towards me. "I won't conceal from you, Mr. Holmes, that we think
in the C.I.D. that you have a wee bit of a bee in your bonnet
over this professor. I made some inquiries myself about the
matter. He seems to be a very respectable, learned, and
talented sort of man."

"I'm glad you've got so far as to recognize the talent."

"Man, you can't but recognize it! After I heard your view I made