Kierkegaard wrote this book in the days following his break up with his fiancee.
In the first part of the book, Kierkegaard describes a philosophy of aesthetics, and in the second part, he deals with ethics.
Kierkegaard writes under the pseudonym "A" in his aesthetic opening. He says that the aesthetic of art is related to pleasure. He finds music to be a direct form of pleasure which elicits powerful responses from the imagination. He praises Mozart for his operas, and he uses Don Juan as an illustration of an important point: That repetition dulls the senses; therefore, aesthetic pleasure leads has hedonic issues, because there is the issue of entertainment or intrigue. As a person repeats an entertaining experience, they learn less, and they often jump from experience to experience without patience.
He describes the true challenge of attaining aesthetic bliss. Boredom, he finds, is compelling us to find something entertaining to consume, because it is an extreme, distasteful emotion that people tend to hate. He notices that Denmark's government is making use of the public outcry against boredom, which is potentially dangerous, because it means the government might have sway if they can entertain efficiently. He mentions once receiving a letter and not opening it for three days because he was more entertained by guessing what it said than he would be by opening it.
Part One ends with "The Seducer's Diary," a famous passage written under the pseudonym "Johannes Climacus." Climacus describes his attempts to attract Cordelia, a beautiful woman. He takes pleasure from the art of seduction, and he attempts to woo her and it works. They become engaged. But, after this, he finds that it was more fun to seduce a girl than to marry her, and he calls of his engagement to Cordelia and decides to pursue someone else.
Part Two is written by interchangeable pseudonyms, "B," or "The Judge." The Judge writes a letter from "B" to "A" (the first pseudonym; remember the envelope). He writes to persuade A that A's life will be more rich and fulfilling if he could only learn to prioritize ethics instead of attaching himself to his desire for artistic entertainment. He writes that the consistency of marriage brings more joy than seduction alone, but that it takes patience and commitment to discover that through time.
He urges A to remember that our common understanding of romance is shaped by art that is designed to entertain, which often stops just before the real sludge of daily life sets in. However, by attaching himself to ethics, The Judge believes that A could save his soul. The key seems to be remembering that although life has an aesthetic value, it also has the aspect of judgment; A is hurting his fate by ignoring the silent, boring values of growth, security, and sacrificial love.
