> I spent ages trying to work out what "who knew more about furniture than most" meant, thinking it would be expanded upon or referenced later.
Assuming it was an intentional, it could be a reference to one particularly violent piece of furniture. (I forget what kind exactly, it's been a while.)
I'm not sure I'd call it furniture, but are you maybe referring to the luggage?
It's furniture when standing, and luggage when walking.
Given it comes immediately after the bit about philosophers comparing memories to furniture, I simply assumed that was meant to be read as “Pratchett, who knew more about the goings on inside people’s heads than most”.