Francis Bacon wrote every letter as five units of two kinds, A and B: A is AAAAA, B is AAAAB, C is AAABA, and so on. Five units of two kinds gives thirty-two combinations, which is enough for the alphabet.
This is the ancestor of binary, and the reason it matters is the second step. Nobody sees a code, because there is nothing to see.
The alphabet made of two things
Francis Bacon wrote every letter as five units of just two kinds, which he called A and B. His clever part was the second step: those units could be carried by anything that came in two forms — two typefaces, tall and short letters, two kinds of thread. The message hides inside an ordinary page. Three hundred years later, computers would use exactly this idea with the two kinds called nought and one.
Print this page and you get a worksheet: how the cipher works, where it came from, and the puzzles to crack, with the machine and the menus left off.
Print this page as a worksheet Its sheet in the pack Try the challengesLonger, harder and written for grown-ups. Worth a look when this page runs out.