Books
Laughter need not be cut out of anything, since it improves everything.
— James Thurber · Selected Letters of James Thurber

Behind the line May contain spoilers.
Our reading
An editorial interpretation.
Laughter is presented as something that can belong anywhere, rather than an interruption that must be removed when matters grow serious. The sweeping claim gives humour a constructive role. Its presence can improve an experience without requiring the underlying subject to become trivial or unimportant.
Context reviewed