Sweetness and light

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 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 prolegomenon 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 1869 book Culture and Anarchy: An Essay in Political and Social Criticism, where "sweetness and light" stands for beauty and intelligence, the two key components of an excellent culture.

"The Battle of the Books" spoofed the famous seventeenth-century Quarrel of the Ancients and the Moderns, a controversy that had raged first in France and then, less intensely, in England, about which was better the Ancient or Modern learning. Should people still model their writings and artistic productions on Greek and Latin authors? Or should they study the (moderns from the Renaissance on), who used living vernacular languages (not dead ones) and produced practical inventions, and new artistic genres that could be read by everyone. In On Ancient and Modern Learning (1697), Swift's patron, the urbane Sir William Temple, had weighed in on the losing side, that of the Ancients, repeating the famous paradox used by Newton that we moderns see further only because we are dwarves standing on the shoulders of giants. Swift has the books come to life and step down from the library shelves to stage a mock-Homeric battle, while the goddess Criticism, a hideous hag, intervenes on the side of her beloved "Moderns" in the manner of the Olympians of yore.

...
Wikipedia