In 1912 in northern Italy, book dealer Wilifred Voynich bought an illuminated codex in an unknown writing system. Containing about 240 pages (though some are missing), the manuscript is written on vellum, and has been carbon-dated to the early 15th C. The manuscript has long been assumed to be a cipher - though that wasn't exactly proven until analysis discovered a semantic pattern in the text; it could have been gibberish - and both amateur and professional codebreakers have taken cracks at it over the years. Nada. From this void of understanding, all manner of crackpot theories have emerged, with an emphasis on the alien/Atlantean memeplex of doom. Having a 15th Century unbroken cipher is like the god of the gaps of the secret history.