Comedy is simply a funny way of being serious.

Peter Ustinov (1921-2004) English actor, author, director

(Attributed)

While I could not find a specific source for this ubiquitous attribution, it does show up in two collections of Ustinov quotations during his lifetime: The Wit of Peter Ustinov, ed. Dick Edwards (1969), and The Quotable Ustinov, no editor given (1995).