Do you know which book these terms come from?

Question

Do you know the title of the book, as well as the author that these two terms come from? And do you know what they mean?

"Inn sewer ants"
"Reflected sound of underground spirits"

This is a bit of a riddle, but if you can work it out, it makes sense. And yes, this actually is from a book written by a well known author.

Answer 1

- [p. 44/39] "'Reflected-sound-of-underground-spirits?'"

Surprising as it may seem (or at least as it was to me), there are quite a few people who do not understand this cryptification of 'economics', even though it is explicitly explained by Terry a bit later, on p. 71/63: 'echo-gnomics'. Some of the confusion perhaps arises from the fact that we don't usually associate gnomes with spirits, as in: ghosts. But I think Terry here simply means spirits (as in: souls) living underground, with the emphasis on the word 'underground'.



Twoflower, an expert in and an enthusiast of inn-sewer-ants (understood by Ankh-Morpork citizens as betting against a ship accidentally sinking, something getting stolen or a building getting burned down)

Answer 2

First book in the discworld series. by Terry Pratchett
"The Colour of Magic"
conversation between Twoflower and Rincewind