Sweetness and light
From The Art and Popular Culture Encyclopedia
Sweetness and light is an English idiom that today is used in common speech, generally with mild irony, to describe insincere courtesy. For example: The two had been fighting for a month, but around others it was all sweetness and light. Originally, however "sweetness and light" term had a special use in literary and cultural criticism to mean "pleasing and instructive", which in classical theory was considered to be the aim and justification of poetry.
Jonathan Swift, the author of Gulliver's Travels, first used the phrase in his mock-heroic prose satire, "The Battle of the Books" (1704), a defense of Classical learning (1704), which he published as a prolegomena to his A Tale of a Tub. It gained widespread currency in the Victorian era, when English poet and essayist Matthew Arnold picked it up as the title of the first section of his in his 1869 book Culture and Anarchy: An Essay in Political and Social Criticism, where "sweetness and light" stands for the intelligence and beauty that art and culture add to life.