The marvelous rebellion of man at all signs reading "Keep Off."

Sandburg’s line wryly celebrates a persistent human impulse: the urge to test boundaries precisely when authority marks them as forbidden. “Keep Off” stands for all prohibitions—legal, social, moral, or merely conventional—that invite curiosity and defiance. Calling this impulse “marvelous” frames rebellion not simply as delinquency but as a creative, life-affirming force that drives exploration, innovation, and the refusal to accept limits as final. At the same time, the phrasing hints at irony: the same contrarian streak that fuels progress can also lead to needless transgression. The quote captures Sandburg’s populist sympathy for ordinary human restlessness and skepticism toward imposed rules.