It could mean pretty much anything. Though I suppose he probably wasn't quite as, er, interesting at the time he said that.

Seriously, though, it has to be in one of the discussions about history and it repeating itself that are so frequent in Erikson's books - Kellanved isn't actually there to say it in person, so somebody has to be quoting him on that. I'd guess that it has something to do with more intelligent people realizing that monstrosities and senseless death happen over and over and over again in history, as indeed they do in that series, whereas the dull-witted don't... but that's just a stab in the dark.

As for reading the book, you should, it's spectacular, second only to its sequel Memories of Ice. Not exactly what you'd call uplifting, though... as you might have cleverly deduced from the previous paragraph.