There are exceptions... When a child first learns that he or she is mortal, I doubt that that is a happy day for him or her. Truths are valuable, but some are rather bitter.
Yes, and I think this is the one big crucial exception... That is the one bit of knowledge that is truly evil. The one datum that is unbearable torture on the mind.
In that sense, one could define an adult mind as a normal (child) mind poisoned by the knowledge-of-death toxin. The older the mind, the more extensive the damage.
Most of us might see it more as a catalyst than a poison, but I think that's insanity justifying itself. We're all walking around in a state of deep existential panic, and that makes us weaker than children.
A monthly thread for posting rationality-related quotes you've seen recently (or had stored in your quotesfile for ages).