The observation that it's easy to try one lie, but hard to try only one. In other words, one lie tends to lead to more lies. The term was coined by Al Giri, professor of philosophy at Loyola University.

The Donation of Constantine was a document supposedly written by the Emperor Constantine, granting the Catholic Church ownership of vast lands in the western Roman Empire. For centuries, it was accepted as authentic, until 1440, when the scholar Lorenzo Valla used textual analysis to expose it as a fraud. Valla's analysis represented the growing influence of Renaissance Humanism, and a new willingness in Europe to question long-held beliefs. More…

The Holy Foreskin of Christ first made an appearance in Europe around 800 ce, when King Charlemagne presented it as a gift to Pope Leo III. Being an actual body part of Christ, it was considered to be incredibly valuable. But rival foreskins soon began to pop up all over Europe. Eventually twenty-one different churches claimed to possess the genuine Holy Foreskin. By 1900, the Church had decided that all the rival foreskins were frauds. More…

According to legend, Pope Joan was a woman who concealed her gender and ruled as pope for two years during the 9th Century. Her identity was exposed when, riding one day from St. Peter's to the Lateran, she stopped by the side of the road and, to the astonishment of everyone, gave birth to a child. The legend is unconfirmed. Skeptics note that the first references to Pope Joan only appear hundreds of years after her supposed reign. More…

Throughout the Middle Ages, Europe hosted a thriving trade in holy relics. But many of the relics, if not almost all of them, were fake. The relics collected and worshipped by medieval Europeans ranged from the mundane to the truly bizarre. Bones or body parts of saints and martyrs were always in high demand. One church proudly displayed the brain of St. Peter until the relic was accidentally moved and revealed to be a piece of pumice stone. More…

At a time when European rulers felt threatened by the growing power of Muslim nations on their borders, a letter suddenly appeared from Prester John, who described himself as a Christian king of vast wealth and power living in the far east. Hopes were raised that Prester John would come to the aid of Europe's Christian nations, and expeditions were sent to search for him. But Prester John was never found. The letter's true author remains unknown. More…

A letter supposedly written by the astrologers of Toledo that began circulating throughout Europe in 1184. It predicted the world would end in September 1186, amidst awful calamities. People were advised to flee their homes and find safety in the mountains. The letter caused panic throughout Europe. Of course, the world didn't end, but that wasn't the end of the letter's career. Variants of it, with names and dates altered, continued to circulate for centuries, and continued to cause panic. More…

Marco Polo's Description of the World, written around 1298, described his travels in China. But did Marco Polo actually travel to China? Some historians have expressed doubts. These scholars point to curious omissions in his book, such as the fact that he never mentions the Great Wall of China nor the Chinese use of chopsticks. They suggest that Polo may have simply compiled information about the Far East from Persian and Arabic guidebooks. More…

This famous cloth bearing the image of a naked man first came to the attention of the public in 1355. Its supporters claim that it was the funeral shroud of Christ. But skeptics dismiss it as a medieval forgery, arguing that: 1) there was a flourishing trade in such false relics; 2) a medieval forger could definitely have created it, despite claims to the contrary; and 3) the man's body is oddly proportioned (his head is too large), which suggests the image is a painting. More…

This popular book (a 'bestseller' for its time) purported to document the travels of an English knight throughout Egypt, Ethiopia, India, Persia, and Turkey. It described bizarre foreign lands and people, such as islanders who had the bodies of humans but the heads of dogs, and a race of one-eyed giants who ate only raw fish and raw meat. The book was widely regarded as factual, even though it was obviously fiction. More…

Stories about the island of Hi-Brazil circulated around Europe for centuries, telling that it was the Promised Land of the Saints, an earthly paradise where fairies and magicians lived. The island was said to be somewhere in the Atlantic, off the coast of Ireland. Based on this information, cartographers of the late-medieval period frequently placed the island on maps. And many explorers even attempted to find it. More…

During the early 15th Century, when a neighboring abbey claimed a portion of the land of Crowland Abbey (located in the Lincolnshire Fens of England) as its own, the Crowland monks presented legal authorities with a volume known as the Historia Crowlandensis, or History of Crowland, to document their historical ownership of the disputed lands. The History was accepted as legitimate, and the Crowland monks won their case. It wasn't until the 19th Century that historians realized the History was, for the most part, an invention. It contained numerous anachronisms, such as referring to monks who had supposedly studied at Oxford, long before the University was founded. It also claimed that many of the monks had lived to ages well past 100. Such longevity would be hard-to-believe today, let alone in the Middle Ages. More…

Jean V d'Armagnac was the penultimate Count of the French province of Armagnac. He became infamous after he fell in love with his younger sister and had two sons with her. He sought approval from the Pope to marry her, but the Pope refused. Undeterred, the Count bribed a papal official to forge a papal bull allowing the marriage. When the Pope learned of this, he excommunicated the Count. Later, King Charles VII's army killed the Count and dragged his body through the streets. More…

As a young man, Michelangelo sculpted a sleeping cupid. He, or an accomplice, then buried it in acidic earth to give it an appearance of great age. The plan was to pass it off as an antiquity, to fetch a higher price. The artificially aged sculpture was bought by Cardinal Raffaello Riario of San Giorgio who, when he learned of the forgery, demanded his money back. But impressed by Michelangelo's talent, the Cardinal didn't press charges. More…

The Voynich manuscript is a mysterious book consisting of pages of hand-written text and crudely drawn illustrations that depict plants, astrological diagrams, and naked women. The text has defied all attempts at translation. One theory is that the book's text was simply gibberish that an alchemist used to impress clients. But no one knows for sure what the book's purpose was. More…

Early modern naturalists used the term "Lusus Naturae" (meaning 'Jokes of Nature') to describe any creature or object that defied classification. The concept represented the belief that Nature enjoyed playing jokes on man by confounding his expectations — in other words, that Nature played hoaxes on man. One famous example of a Lusus Naturae was the "Vegetable Lamb." Believed to be a real creature, this was a lamb from whose belly grew a thick stem firmly rooted in the ground. Thus, it was part plant, part animal, but didn't belong wholly in either category. More…

Michel de Notredame, better known as Nostradamus, rose to prominence as an astrologer supported by the patronage of Queen Catherine de Médici. He wrote prophecies in an ancient form of French worded so ambiguously that it could be interpreted to mean almost anything a reader desired. This artful ambiguity has allowed his followers to credit him with predicting many events. Although his supposed predictions are only ever noticed after the events have occurred. More…

Martin Guerre, a French peasant, married Bertrande de Rols in 1538. But in 1548, he disappeared. Eight years passed, and then Martin suddenly returned. Or did he? Bertrande accepted him as her husband, but the uncle became suspicious and accused him of being an imposter. The case went to trial. The court was about to declare him genuine, when suddenly the actual Martin Guerre showed up. He had been serving in the army, where he had lost a leg. More…

Carlo Sigonio was a highly respected Italian scholar who specialized in the history of Rome. Around 1583, he claimed that he had discovered a new complete work by the great Roman orator Cicero, titled De Consolatione or the Consolation. In it Cicero grieved for his daughter's death. Only small fragments of this work had ever been found before. The discovery of this manuscript caused great excitement, but when other scholars read it, the general consensus was that it had to be a fake as it contained numerous anachronistic phrases and Italian mannerisms that Cicero would never have used. Sigonio stubbornly defended the work, but today it is still regarded as being a forgery. Sigonio probably wrote the book himself, perhaps to display his mastery of Ciceronian scholarship.

Reports spread of a young Silesian boy who had miraculously grown a golden tooth. A professor of medicine investigated and determined that the boy did indeed have a gold tooth. He attributed its growth to an unusual alignment of the planets. But the daily pressure of chewing eventually wore down the gold, revealing it to be a thin layer of metal skillfully fitted over the tooth. Although a fraud, it was the first documented case of a gold crown fitted for a tooth. More…

A pamphlet published in Paris described the case of a woman who had given birth to a son, even though her husband had been absent for four years. When charged with adultery, the woman claimed innocence, explaining that her husband had impregnated her in a dream. The court accepted this argument. The report of this ruling caused an uproar throughout Paris, but upon investigation the pamphlet was revealed to be a hoax. More…

Mother Shipton was said to be a sixteenth-century Yorkshire seer who made a number of startlingly accurate predictions. However, it is uncertain whether she actually existed, and many of the predictions attributed to her are outright hoaxes written long after the sixteenth century. During the period when she was supposedly alive, there were no written references to her or her predictions. More…