Horace (65 BC - 8 BCE) was a Roman poet, satirist, essayist in the century before the Christian or Common era.
Two quotations from Horace inspire the classical theory that literature has two purposes, which may overlap:
2) to instruct or educate, to inform, guide, or provide models of behavior, whether positive or negative; sometimes to offer a moral or lesson; to model successful style for readers to admire as advances for other writers or artists to imitate.
Translations or adaptations of Horace's aphorisms: "He gains everyone's approval who mixes the pleasant with the useful. " + "Often the truth spoken with a smile will penetrate the mind and reach the heart; the lesson strikes home without wounding because of the wit in the saying."
Thus, the purpose of literature is "to entertain and educate"—distinct but not exclusive purposes.
Compared to philosophy, Literature also concerns ideas, the mind, opinions, etc., but less directly. Instead of being analyzed, thoughts or themes are represented through characters, actions, stories—the mimesis or imitation of our sensory or experiential world.
The balance or prominence of "learning" vs "pleasure" varies with genre, history, purposes in reading, etc.
Synonyms and examples
to entertain = "escape"; "I like a good story"—i. e., being swept away into another world richer or more exciting than our own
examples that emphasize entertainment: pure entertainment = popular literature, which sells well and is read avidly but tends to disappear quickly like other consumer items, e. g., TV shows, most movies, most hit songs. They're all very right for the moment and may make serious money, but they get overexposed and stale, creating need for new products to replace them, and soon the changing culture and its consumers can't imagine liking what they liked before except as nostalgia.
examples: lectures, editorials, sermons, bible studies, histories, classic literature, classical music, museum art. Few people get rich in these areas, and the products are "underexposed" rather than overexposed.
Underexposed: For instance, Houston has many "pop music" stations but only 1 classical station—a public radio station that will soon discontinue. After 20+ years, in the early 2000s the commercial classical station was sold to become urban dance, then religious, and probably something else by now.
Products like classical music are rarely as overwhelmingly right for a single moment than a pop-culture product, but they usually don't pop and disappear as fast. Nearly all popular music and art disappears within the lifetime of its audience.
Aristotle, Poetics IV: "to learn gives the liveliest pleasure, not only to philosophers but to people in general."
In an 1818 letter on women's education, Thomas Jefferson uses Horace's formula twice--see bolded phrases:
A great obstacle to good education is the inordinate passion prevalent for novels, and the time lost in that reading which should be instructively employed. When this poison infects the mind, it destroys its tone and revolts it against wholesome reading. Reason and fact, plain and unadorned, are rejected. Nothing can engage attention unless dressed in all the figments of fancy, and nothing so bedecked comes amiss. The result is a bloated imagination, sickly judgment, and disgust towards all the real businesses of life. This mass of trash, however, is not without some distinction; some few modelling their narratives, although fictitious, on the incidents of real life, have been able to make them interesting and useful vehicles of sound morality. Such, I think, are Marmontel's new moral tales, but not his old ones, which are really immoral. Such are the writings of Miss [Maria] Edgeworth [novelist, 1786-1849], and some of those of Madame Genlis [1746-1830, French author & educator]. For a like reason, too, much poetry should not be indulged. Some is useful for forming style and taste. Pope, Dryden, Thompson, Shakspeare, and of the French, Molière, Racine, the Corneilles, may be read with pleasure and improvement.