Abraham Lincoln may have been a world-class orator, but one of his famous letters—known as one of the best English-language letters ever written—was "almost certainly" not authored by the former president. According to a press release, Lincoln sent a letter to a woman named Lydia Bixby in November 1864 after Bixby lost her sons in the Civil War. “I feel how weak and fruitless must be any words of mine which should attempt to beguile you from the grief of a loss so overwhelming,” Newsweek quotes the letter as saying. “But I cannot refrain from tendering to you the consolation that may be found in the thanks of the Republic they died to save.” As the letter gained notoriety for its prose, historians started to debate if it was actually written by Lincoln's secretary, John Hay.
A team of forensic linguistic experts may have finally solved the mystery. With the original letter missing for more than 150 years and both Hay and Lincoln long dead, the researchers turned to a process called n-gram tracing, in which a computer searches for recurring strings of words, or linguistic forms. Time has an in-depth explainer of how n-gram tracing works, and researchers have published a presentation on their work here. A similar method was used in 2013 when sussing out that author Robert Galbraith was actually JK Rowling. Researchers used n-gram testing on 500 texts by both Hay and Lincoln, then tested the Bixby letter. In 90% of tests, Hay was identified as the author of the letter. The other 10% were inconclusive, with Lincoln never once being identified as the letter's writer. (A new theory could explain Mary Todd Lincoln's odd behavior.)