The Voynich manuscript
The Voynich Manuscript is a manuscript possibly written in 15th century in Lojban language.
It has been suggested that Leonardo da Vinci, an Italian Renaissance polymath, was somehow connected with time travelers from the future that spoke Lojban. The appearance of the Voynich Manuscript can be clearly connected with his efforts to teach Lojban to people around him. The possibility of completely altering the history because of these time travels could have driven him away from this challenge. Thus the manuscript remained the only document written in a future language.