'Let There Be Light' is a science fiction short story by American writer Robert A. Heinlein, originally published in Super Science Stories magazine in May 1940 under the pseudonym Lyle Monroe.
It is the second story in his Future History and was included in the first collection, The Man Who Sold the Moon, but was omitted from the omnibus collection The Past Through Tomorrow. This story draws on Heinlein's early leftist ideas, and makes references to George Bernard Shaw's The Apple Cart.