Chapter II.

On the First Mode of Interchange, called Direct Primary Transposition,
Its Subdivisions, and its more Simple Form.

The first General Mode is Primary Transposition, which takes place when one letter is transposed and substituted for another letter which, in accordance with the common method of writing, should have been used, and is endowed with the Power of that other. This description gives a rather general definition of the term; see the preceding chapter, ad fin.  See also herm. Hugo, De Prim. 3crib.Orig., c.17.  there are, as I must repeat from the preceding chapter, three kinds of Primary Transposition. In the present chapter I shall begin the consideration of the first of these.

The first kind of Primary Transposition is that which I call Direct Transposition.  It is also called Transposition in its simple form, Transposition properly taken, and Transposition par excellence; but in order to distinguish it form the other kinds, its meaning is very properly defined by a limiting work.  Why this is so, I have already intimated in the preceding chapter.  This direct Transposition is of a single letter, or of two letters taken together, or of three letters taken together.

Direct Transposition of a single letter, again, is not confined to one method, but is accomplished in three different ways; whence Transposition is further subdivided into; first, Simple Transposition, which takes place when the letters are transposed with reference to a complete alphabet; secondly, Mutual Transposition, which takes place when, two groups being made, the letters of a single alphabet are mutually interchanged one with another; thirdly, Mixed Transposition, wherein the letters are transposed, is part mutually, and in part simply. Whence arise three Special Modes, the first of which is discussed in this and the three following chapters, while the other two are treated in Chapters Six and Seven.

Simple Transposition, then, which is performed with reference to a complete alphabet, takes place through the Natural, Arbitrary, or Fortuitous disposition of Transpositive alphabets, which are placed beneath the complete alphabet.

Natural Simple Transposition is so called from the fact that, in the formation of the table, the natural order of the alphabet is to this extent observed, that in each line we begin with the letter A, in whatever part of the line the letter be found, and then join to the end of the line the beginning of the same line.  This Transposition is accomplished by three different processes: namely the Direct process, the Inverted process, and the Successive process.

Direct Natural Transposition takes place when we write the letter B for A, or C for A, or, even, D for A, and continue the process through the whole alphabet.  This is the Mode said to have been used by Gaius Julius Caesar, and Probus, the gramatian, wrote a book on Caesar’s use of it (Aulus Gellius, Noct.Attic., 12.2.).  An understanding of this Mode in all its workings can be obtained in no better way than by consulting the table given above, near the beginning of the Twelfth Chapter of Book 3.; in which place we have the various Modes arising from this process, as set forth in steganographic form, for the whole alphabet, by Trithemius. Trithemius has also in his General Key given an explanation for this Mode and illustrated it by an example. I insert his words here: