Directly I saw the half-faded parchments I recognised that the cipher
which those early Jesuit writers had used was a very simple one. This,
I may explain to the uninitiated, is not so difficult a matter to
observe as they might perhaps think. Some very simple considerations
guided me to this conclusion. For instance, unlike the cipher in use by
the founder of St Bruno, there were practically no figures in the
manuscripts, and by that I gathered the cipher was complete in the
alphabet in use, and did not refer to any book, like the institutes of
St Bruno. The one thing that does puzzle and sometimes confound
experts is to adopt a book, as Bruno Delganni had done, and then to put
in the record simply figures that related to letters in this volume.
That, however, is not always quite safe. The expert looks in the
manuscript for the letter that appears most often, and he decides,
perhaps, that that is "e," the second "i," and so on according to the
letters that are most frequently used in the language in which he
believes the document to be written, and by this simple means he can
often construct the entire code alphabet.
On some such method I too proceeded with the inspection of the
manuscripts in question, and found that the letter that appeared the
most often therein was a certain letter that was not often used in any
language. I, therefore, turned the alphabet round thus: