[He starts to leaf through the book as he talks.]

I'm totally unprepared to reciprocate such generosity. "Reciprocate" is a great word, isn't it? I had no idea anyone would have gifts for me. My heart has been both filled with the spirits of generosity and guilt. But I'm grateful for this! I'll have to make it up, somehow. Mark my words.

[Is that a promise or a threat?]