"Ut vero suspicio omnis absit, aliud Juventum subijciemus, quod certe, cum Adolescentuli essemus Parisiis, excogitavimus; nec etiam adhuc visa vobis res digna est, quae pereat. Habet enim gradum Ciphrae altissimum; nimirum ut _Omnia per Omnia_ significari possint: ita tamen, ut Scriptis quae involuitut, quintuplo minor sit, quam ea cui involvatur: Alia nulla omnino requiritur Conditio, aut Restrictio. Id hoc modo fiet. Primo, universae literae Alphabeti in duas tantummodo Literas soluantur, per Transpositionem earum. Nam Transpositis duarum Literarum, per Locos quinque, Differentiis triginta duabus, multo magis viginti quatuor (qui est Numerus Alphabeti apud nos) sufficiet. Huius _Alphabeti_. Exemplum tale est." * * * * * "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. A B C D E F G H aaaaa aaaab aaaba aaabb aabaa aabab aabba aabbb I K L M N O P Q abaaa abaab ababa ababb abbaa abbab abbba abbbb R S T V W X Y Z baaaa baaab baaba baabb babaa babab babba babbb "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. F L Y aabab ababa babba "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: