“But for avoiding suspicion altogether, I will add another contrivance, which I devised myself when I was at Paris in my early youth, and which I still think worthy of preservation. For it has the perfection of a cipher, which is to make anything signifying anything; subject however to this condition, that the infolding writing shall contain at least five times as many letters as the writing infolded; no other condition or restriction is required. The way to do it is this: First let all the letters of the Alphabet be resolved into transpositions of two letters only. For the transposition of two letters through five places will yield thirty-two differences; much more twenty-four, which is the number of letters in our Alphabet. Here is an example of such an Alphabet.

ABCDEFGH
aaaaaaaaabaaabaaaabbaabaaaababaabbaaabbb
IKLMNOPQ
abaaaabaabababaababbabbaaabbababbbaabbbb
RSTVWXYZ
baaaabaaabbaababaabbbabaabababbabbababbb

“Nor is it a slight thing which is thus by the way effected. For heare we see how thoughts may be communicated at any distance of place by means of any objects perceptible either to the eye or ear, provided only that those objects are capable of two differences; as by bells, trumpets, torches, gunshots, and the like. But to proceed with our business. When you prepare to write, you must reduce the interior epistle to this bi-literal alphabet. Let the interior epistle be:

Fly.
Example of reduction.
FLY
aababababababba

“Have by you at the same time another alphabet in two forms; I mean in which each of the letters of the common alphabet, both capitals and small, are exhibited in two different forms,—any forms that you find convenient.”

[For instance, Roman and Italic letters; “a” representing Roman and “b” representing Italic.]

“Then take your interior epistle, reduced to the bi-literal shape, and adapt it, letter by letter, to your exterior epistle in the biform character; and then write it out. Let the exterior epistle be:

“Do not go till I come.”
Example of reduction
FLY
aababababababba
DONOTGOTILLICOM—E
do notgo tillI come

From the above given dates it would almost seem as if Bacon had treated the matter in a purely academic manner, and had drawn out of his remembrance of his younger days a method of secret communication which had not seen any practical service. Spedding mentions in his book “Francis Bacon and his Times” that Bacon may have got the hint of the ‘bi-literal cypher’ from the work of John Baptist Porta, “De occultis literarum notis,” reprinted in Strasburg in 1606, but the first edition of which was published when Porta was a young man. It is however manifest from certain evidence, that Bacon practised his special cipher and used it for many years. Lady Bacon, mother of the philosopher, writing in 1593, to her son Anthony, elder brother of Francis, speaking of him, Francis, says, “I do not understand his enigmatical folded writing.” Indeed it is possible that many years before he had tried to have his invention made use of for public service. His was an age of secret writing. Every Ambassador had to send his despatches in cipher, for thus—and even then not always—could they be safe from hostile eyes. The thousands of pages of reports to King Philip made by Don Bernardino de Mendoza, the Spanish Ambassador at the Court of Queen Elizabeth, before the time of the Armada, were all written in this form; the groaning shelves of the records at Simancas bear evidence of the industry of such political officials and of their spies and secretaries. An ambitious youth like Francis Bacon, son of the Lord Keeper, and so traditionally and familiarly in touch with Court and Council, who in his baby days was addressed by Elizabeth as her “young Lord Keeper,” and who spent the time between his sixteenth and eighteenth years in the suite of the English Ambassador in Paris, Sir Amyas Paulet, must have had constant experience of the need of a cipher which would fulfill the conditions which he laid down as essential in 1605—facility of execution, impossibility of discovery, and lack of suspiciousness. When, in a letter of 16 Sept. 1580, to his uncle Lord Burghley, he made suit to the Queen for some special employment, it is possible that the post he sought was that of secret writer to Her Majesty. His letter, though followed up with a more pressing one on 18th October of the same year, remained unanswered. Whatever the motive or purpose of these last two letters may have been, it remained on his mind; for eleven years later we find him again writing to his uncle the Lord Keeper: “I ever have a mind to serve Her Majesty,” and again, “the meanness of my estate doth somewhat move me.” In the interval, on 25th August, 1585, he wrote to the Right Hon. Sir Francis Walsingham, Principal Secretary to the Queen: “In default of getting it, will go back to course of practice (at Bar) I must and will follow, not for my necessity of estate but for my credit’s sake, which I fear by being out of action will wear.” His brother Anthony spent the best part of his life abroad, presumably on some secret missions; and as Francis was the recipient of his letters it was doubtless that “folded writing” which so puzzled their mother which was used for the safety and secrecy of their correspondence. Indeed to what a fine point the biliteral method must have been brought by Bacon and his correspondents is shown by the extraordinarily minute differences given in his own setting forth of the symbols for “a” and “b” etc., in the “De Augmentis” of 1623 and later. In the edition printed in Latin in Paris the next year, 1624, by Peter Mettayer, the differences, possibly through some imperfection of printing, are so minute that even the reader studying the characters set before him, with the extra elucidation of their being placed under their proper headings, finds it almost impossible to understand them. The cutting for instance of the “n” which represents “a” and that which represents “b” seems, even after prolonged study, to be the same.