Cloud cuckoo land is a state of absurdly, over-optimistic fantasy or an unrealistically idealistic state where everything is perfect. Someone who is said to "live in cloud cuckoo land" is a person who thinks that things that are completely impossible might happen, rather than understanding how things really are. It also hints that the person referred to is naive, unaware of realities or deranged in holding such an optimistic belief.
In the modern world, a "cloud cuckoo lander" is defined as someone who is seen as "crazy" or "strange" by most average people, often doing or saying things that seemingly only make sense to themselves, but also exhibit cleverness at times in ways no one else would think of.
Cockaigne, the land of plenty in medieval myth, can be referred to as the modern day cloud cuckoo land. It was an imaginary place of extreme luxury and ease where physical comforts and pleasures were always immediately at hand and where the harshness of medieval peasant life did not exist.
Aristophanes, a Greek playwright, wrote and directed a drama The Birds, first performed in 414 BC, in which Pisthetaerus, a middle-aged Athenian persuades the world's birds to create a new city in the sky to be named Nubicuculia or Cloud Cuckoo Land (Νεφελοκοκκυγία, Nephelokokkygia), thereby gaining control over all communications between men and gods. The German philosopher Arthur Schopenhauer used the word (German Wolkenkuckucksheim) in his publication On the Fourfold Root of the Principle of Sufficient Reason in 1813, as well as later in his main work The World as Will and Representation and in other places. Here, he gave it its figurative sense by reproaching other philosophers for only talking about Cloud-cuckoo-land. The German philosopher Friedrich Nietzsche refers to the term in his essay "On Truth and Lying in a Nonmoral Sense." Author Edward Crankshaw used the term when discussing the Deak-Andrassy Plan of 1867 in his 1963 book The Fall of the House of Habsburg (Chapter 13, "The Iron Ring of Fate").
The phrase has been used by British and United State politicians as well as writers. Margaret Thatcher famously used this phrase in the 1980s: "The ANC is a typical terrorist organisation... Anyone who thinks it is going to run the government in South Africa is living in cloud-cuckoo land." Bernard Ingham, Margaret Thatcher's spokesman, who, when asked if the ANC might overthrow the government of South Africa by force, replied: "It is cloud-cuckoo land for anyone to believe that could be done". Ann Widdecombe, British MP used the phrase in a debate on drug prohibition with a representative of Transform Drug Policy Foundation: "...it is cloud cuckoo land to suggest that [people who don't currently use heroin would not start using it if it became legal]".
Newt Gingrich referred to Barack Obama's claim that algae could be used as a fuel source as cloud cuckoo land. Henry A. Wallace, U.S. Secretary of Agriculture (later U.S. Vice President in Franklin D. Roosevelt's third term) used the term to describe the unrealistically inflated value of stocks on the New York Stock Exchange just before the crash of 1929 that signaled the onset of the Great Depression. In his 1936 book, Whose Constitution? An Inquiry into the General Welfare, Wallace describes a cartoon in a popular weekly magazine which "pictured an airplane in an endurance flight refueling in mid-air, and made fun of the old fashioned economist down below who was saying it couldn't be done. The economic aeroplane was to keep on gaining elevation indefinitely, with the millennium just around a cloud" (p. 75). Wallace wrote that Wall Street's practice of lending money to Europe after World War I "to pay interest on the [war reparations] debts she owed us and to buy the products we wanted to sell her ... was the international refueling device that for 12 years kept our economic aeroplane above the towering peaks of our credit structure and the massive wall of our tariff, in Cloud-Cuckoo Land".
Paul Krugman used the phrase referring to inadequate German economic politics toward failing members of the European Union: "Basically, it seems that even as the euro approaches a critical juncture, senior German officials are living in Wolkenkuckucksheim—cloud-cuckoo land." (June 9, 2012). Yuri N. Maltsev, an Austrian economist and economic historian, uses the term to describe the lack of promised results in the communist states in his forward to 1920 essay by Ludwig von Mises: "Today, the disastrous consequences of enforcing the utopia on the unfortunate populations of the communist states are clear even to their leaders. As Mises predicted, despite the cloud-cuckoo lands of their fancy, roasted pigeons failed to fly into the mouths of the comrades."
The phrase has been used in poetry, music, film and by writers. Cloudcuckooland, a poetry collection by Simon Armitage. Cloudcuckooland, the first album by the Lightning Seeds, released in 1990. Cloud Cuckooland is the name of the eighth world found in the video game Banjo-Tooie. Cloud Cuckoo Land is the name of a magical realm, hidden inside a cloud featured in The Lego Movie. Radiohead uses the term in the lyrics of their song Like Spinning Plates. Publisher and editor Gary Groth uses the term in the title of his review of Scott McCloud's book Reinventing Comics.