Yes.But to its credit, at least Mort Walker Inc. seems to know it.
Maybe Tolstoy started this way.
This Doonesbury is more smart than it is funny, but we here at The Comics Section are a cultured sort, so we can appreciate this kind of thing.
Considering it's appearing in a Ziggy cartoon, this is a very clever joke. It contains two parts. First, it's hilarious because service at the Post Office is slow. Second, it's hilarious because service at the Post Office is expensive. Granted, neither of these potential sources for humor is even remotely original, and at least one of them is rather strikingly false, but for Ziggy it really is an impressive piece of art.
What Billy means is that it's hard to be saint because of the way you're constantly having to live up to other people's expectations, their perfected image of you, the image they reproduce in windows and paintings and books.