The Voyage of the Dawn Treader
Of course Caspian's ship was not that horrible thing, a galley rowed by slaves. Oars were used only when wind failed or for getting in and out of harbour and everyone (except Reepicheep whose legs were too short) had often taken a turn. (2.43)
There was not much difficulty in settling the matter once Eustace realised that everyone took the idea of a duel quite seriously and heard Caspian offering to lend him a sword, and Drinian and Edmund discussing whether he ought to be handicapped in some way to make up for his being so much bigger than Reepicheep. (2.68)
"Your Majesty's tender years," said Gumpas, with what was meant to be a fatherly smile, "hardly make it possible that you should understand the economic problem involved. I have statistics, I have graphs, I have – "
"Tender as my years may be," said Caspian, "I believe I understand the slave trade from within quite as well as your Sufficiency. And I do not see that it brings into the islands meat or bread or beer or wine or timber or cabbages or books or instruments of music or horses or armour or anything else worth having. But whether it does or not, it must be stopped."
"But that would be putting the clock back," gasped the Governor. "Have you no idea of progress, of development?"
"I have seen them both in an egg," said Caspian. "We call it Going bad in Narnia. This trade must stop." (4.25-28)