Not a little of the discussion concerning the existence of the Biliteral Cipher in the works of Francis Bacon has centered about the fact that Italian type in two forms in the same text existed in books printed before Bacon's time, that this use increased during the period in which he wrote, and was continued long after his death. This has led to many conjectures. I have in various ways sought to make plain what seems to me the real explanation, and may, in this connection, repeat what is already familiar to some readers. Many, however, do not understand it, and this is my excuse for further brief reference to the subject. It is conceded that Bacon was the inventor of the Biliteral system .
Inventions usually result from the suggestion or adaptation of something already in existence.
How mixed fonts came to be used before Bacon's time, is impossible to ascertain. The success and secrecy of his plan became at once apparent, and it was continued in his writings. The very success of its hiding caused him at length to fear that he had done his work too well, and that he must give some hint of its existence, or it would never be discovered. In 1605, we have the first mention of a Biliteral Cipher, but it was not until 1623 that the full explanation of it was given, after it had been in use forty-four years. I have found the cipher in Bacon's works up to 1635.