“The trouble with having an open mind, of course, is that people will insist on coming along and trying to put things in it.”

What does it mean?

"An open mind" means being willing to consider new ideas. Pratchett pictures it as a real open container that annoying people keep trying to fill with their opinions.

Key vocabulary

open mind

willingness to listen to new ideas

insist on

keep doing something even when others don't want it