That's interesting, considering who the character is. I googled up some context, and Quixote is in one of his lucid phases here, where he speaks with wisdom on everything except himself.
Yeah, it's an ironic quote. For what it's worth, I also see some shades of GEB in this.
This is our monthly thread for collecting these little gems and pearls of wisdom, rationality-related quotes you've seen recently, or had stored in your quotesfile for ages, and which might be handy to link to in one of our discussions.