Humor has to surprise us; otherwise, it isn't funny. It's a death knell for a writer to be labeled a humorist because then it's not a surprise anymore.
The Meaning of This Quote
This quote means that to be funny, a joke has to be unexpected. It’s no good if the audience can easily predict the punchline. It’s also bad for a writer to be known as someone who writes humorous works, as then the jokes may become too predictable.