Agatha Christie wrote romance novels under the name Mary Westmacott.

Mystery stories require a meticulous structure, and emotions typically don’t drive the plot. This worked out well for Agatha Christie, who liked her public persona to be somewhat guarded, especially after her infamous 1926 disappearance caused a media ruckus. But Christie found a way to express herself more deeply while still maintaining her privacy: She wrote several semi-autobiographical romance novels under a pen name, Mary Westmacott. The alias allowed Christie to be emotionally vulnerable — and the books received rave reviews.

“The Westmacott [novels] always said things that Agatha couldn’t express any other way,” biographer Laura Thompson wrote in Agatha Christie: A Mysterious Life. These books gave Christie an outlet to explore her fraught relationship with her first husband Archie Christie, reflect honestly (and sometimes harshly) on motherhood, and unearth past trauma. In the Westmacott novel that most closely parallels her own life, Unfinished Portrait (1934), a woman reeling from losses similar to those experienced by Christie meets a handsome painter on an exotic island who listens to her painful life story while creating her portrait. 

The Westmacott books were a valuable, anonymous outlet to Christie from 1930 until 1949, when her identity was revealed in the “Atticus” gossip column of the Sunday Times. She published two more books under the pseudonym after that, but insisted that her real name stay out of the promotion.

Leonardo da Vinci did most of his writing backward.

Famed Renaissance polymath Leonardo da Vinci left behind thousands of pages of notes and diagrams from his many pursuits in math, anatomy, botany, science, engineering, and art — he created more than 200 illustrations with notes on flight alone. Leonardo had groundbreaking ideas on everything from human anatomy to bridge design, and even the writing itself is impressive: Most of it is written from right to left, in a mirror image of ordinary European script. He only wrote left to right when someone else needed to read it. He also used his own form of shorthand.

Leonardo never directly explained why he wrote this way, but there are a few prevailing theories. It may have been simply practical: The artist was most likely left-handed, and writing left to right could get messy using a pen and ink. He also may have been trying to keep his ideas secret from potential copycats, or even trying to hide his work from the Roman Catholic Church. While Leonardo’s artwork is rich with religious symbolism, he was also a skeptic, and some of his ideas would have been at odds with the teachings of the church. After Leonardo’s death, his loose-leaf notes went to his student Francesco Melzi, an Italian painter. They were bound into several volumes, mirror writing and all, and soon began circulating among European elites as collector’s items. They are still kept in museums and private collections today.

Mary Shelley wrote “Frankenstein” after being challenged by Lord Byron.

Mary Shelley’s Gothic masterpiece Frankenstein is one of the horror genre’s most formative works, but it may have never existed if not for a playful challenge. In 1816, Shelley — who was then unmarried and known by the surname Godwin — vacationed at Villa Diodati on Lake Geneva in Switzerland. She was accompanied by her future husband Percy Bysshe Shelley, her stepsister Claire Clairmont, English poet Lord Byron, and Byron’s physician John William Polidori. Weather conditions were abnormally unpleasant at the time due to the lingering effects of the eruption of Indonesia’s Mount Tambora the previous year, forcing the group to largely remain indoors. Amid the dark and frigid evenings of that “Year Without a Summer,” the weary vacationers read and debated literary works late into the night, most notably horror stories and macabre poems that seemed appropriate given the gloomy weather outside.

As the days progressed, Lord Byron issued a challenge to those in attendance to write a scarier, more compelling horror story than the ones they’d been reading. Polidori eagerly and immediately complied, later publishing his novella The Vampyre in 1819, but Shelley struggled to find inspiration at first. That all changed after a ghoulish visage came to her one stormy night, which the author recounted in an 1831 preface to Frankenstein, writing, “I saw the hideous phantasm of a man stretched out, and then, on the working of some powerful engine show signs of life and stir with an uneasy, half-vital motion.” Shelley began work on what became her magnum opus, and effectively “won” Lord Byron’s challenge with the publication of the 1818 novel Frankenstein; or, the Modern Prometheus.