Rugg used an informal version of the Verifier method to re-assess previous work on the Voynich manuscript, a manuscript widely believed to be a ciphertext based on a code which had resisted decipherment since the manuscript's rediscovery by Wilfrid Voynich in 1912. Previous research had concluded that the manuscript contained linguistic features too complex to be readily explicable as a hoax, and too strange to be explicable as a transliteration of an unidentified language, leaving an uncracked cipher as the only realistic explanation.