What part of it are you uncertain about? Do you just think that it's overstating things to think that rationality alone can "cure most of the ills from which the world is suffering"? Or are you actually questioning the wisdom of rationality?
I might just be suffering from availability bias since I was reading about the French Revolution right before I read the quote, but I was thinking that so much of what we do that is non-rational (not based on explicit reasoning or weighing of evidence) could be adapted to our social environment through memetic evolution. If this was the case, dropping norms of behavior or social institutions simply because we don't have sufficient rational justification for them might prove disastrous.
Does this sound crazy or am I making sense?
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.