Is my understanding of the following sentence correct?
I understand it as: No one had warned Caspian that Giants are not at all clever, because no one in these later days remembered that they are not clever at all. they have forgotten about it.
No one had warned Caspian (because no one in these later days of Narnia remembered) that Giants are not at all clever. Poor Wimbleweather, though as brave as a lion, was a true Giant in that respect.
