Saturday, October 22, 2005

A mysterious excuse for a biography of Roger Bacon

kw: book reviews, nonfiction, unknown scripts, medieval scholarship

One of my favorite exercises at the end of a work day is to open the newspaper and solve the daily cipher. These are kept simple by not enciphering the blank, though they can be tricky because they are too short for statistical methods to be of much use. Perhaps you know that universal mystery spy, Etaoin Shrdlu, or his sidekick Etaison Hurdl: these are mnemonics for the order of most frequent letters in 20th- and 19th-century newspaper prose, respectively. However, many, many of the quotes I decipher are quite short of E's or T's, and may have none entirely.

There are many tricks the puzzle columnist can play. For example, a single loose character usually refers to I or A, and you can use the fact that I is rarely found at the end of words to help discern which, early on in a solution. However, I have seen this: "OZN B RNSNATOKLS", which solved to "the X generation".

The medieval scholar Roger Bacon, and his Elizabethan-era namesake Francis Bacon, were both intimately familiar with codes, ciphers, and other methods of steganography (covered writing or hidden writing). Roger Bacon wrote of "Seven Ways of Concealing Secrets." They were

  1. hiding a message "under characters and symbols," one kind of a Code;
  2. hiding it "in enigmatical and figurative expressions," another kind of Code;
  3. writing in a shorthand, such as leaving out vowels in a script like Hebrew that doesn't have them, a Shorthand Cipher;
  4. Ciphers, where invented symbols, or alphabetic symbols in a different order, are substituted for the original letters, and possibly punctuation;
  5. Ciphers with admixed characters, invented or borrowed, Null-padded Ciphers;
  6. complete artificial languages, which are more complex types of Codes;
  7. writing with even more brevity than an ordinary shorthand, possibly with lots of null material padding it. One could call this a Shared-Milieu Code, intelligible only between persons with a similar professional jargon.

Lawrence and Nancy Goldstone have written a sort of mixed biography, partly a biography of Roger Bacon, and partly that of a remarkable document, today called the Voynich Manuscript. In The Friar and the Cipher: Roger Bacon and the Unsolved Mystery of the Most Unusual Manuscript in the World, the Goldstones present a brief history of cryptography, of the Manuscript, and of the man who is its most likely creator.

From his writings, it is known that Roger Bacon was very concerned with concealing some of his writings, because of the scrutiny of the medieval Church. In his days, the Church had the chance to adopt an attitude toward science that embraced experience and experimental evidence, embracing what we call scientific knowledge, while making it subservient to the knowledge obtained by Faith. Instead, the Pope and cardinals rejected this way, choosing instead to deify the atheist Aristotle, who perferred inductive reasoning from imagined premises to deduction from observation. I wonder what things would be like today, if scientific advancement began in the 1200s rather than the 1600s?

As it was, Roger Bacon, who is sometimes called "the father of the scientific method," was in danger, and for some time imprisoned, because of his support for an anti-Aristotelian philosophy. Thus, during his decades of obscurity (he lived eighty years), it is likely he had plenty of time to put together a nearly 300 page document, entirely enciphered (at least), with enigmatic illustrations that are likely also encoded, or at least allegorical. This illustration (trimmed from one of the scans in the Beinecke Library website) shows a portion of one page; the text is accompanied by an apparently botanical drawing, but of no plant known.


I find it quite fascinating that, while the document is attributed to Roger Bacon, and contains a seeming key in a different cipher that translates to a Latin message referring to him, it is by no means certain, either that he composed it, or indeed that it was composed in the Century or locale in which he lived. After much reasoning on both sides of that issue, researchers in favor of Bacon's authorship fall back on the view that there is no other viable candidate...except perhaps Francis Bacon, who lived five hundred years later. But where he could have got such a store of 400-year-old, unused (!) paper is a bigger puzzle.

Is it a hoax? If it is, it is clearly the most elaborate, embodying by far the greatest amount of labor and diligence, of all hoaxes in history. Yet its script has been attacked by the best cryptanalysts of four centuries. The most controversial proposed decipherment is that of William R. Newbold, in the 1920s.

He used a complicated scheme of cipher (I keep wanting to spell it cypher!) decoding, anagrams, and punning rhymes, to produce quite a lot of rather plausible material. His decipherments cannot be conclusively discounted, and nobody else has come close to anything better.

Analysis of character frequencies provides only a partial clue. Languages contain redundancy, to aid a reader in getting a clear meaning. This redundancy varies. Complex languages such as English and Russian have a lot more redundancy than some. The languages with the least redundancy are Polynesian tongues, and wholly artificial languages such as Esperanto. The Voynich script has a level of redundancy—at the character level—that is right on a par with a Polynesian language.

There are just about a dozen examples of wholly unknown scripts. Most supply too little material for a useful cryptographic or linguistic analysis, and most are probably actual language scripts, written in 'clear text' for those who knew the language at the time. The Voynich Manuscript is the largest sample of an unknown script that is known (or almost certain) to be enciphered. Will its code ever be cracked? Perhaps it was, by Newbold, and perhaps not; perhaps someday, perhaps never. That is the body of a good mystery.

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