I never understood why Linus only sometimes, and not very often, wears his glasses. When I say I've always wondered that, I always wondered that since I was a little kid and about to ask who are god's parents.
I remember the time when he got his glasses and didn't like them. There was also a bit where Snoopy was stealing his glasses because he thought they would make him look distinguished. But it seems they vanished in later years.