“The technique was at least moderately well known, for Ibn Khaldūn wrote in The Muqaddimah: “Occasionally, skillful secretaries, though not the first to invent a code [and with no previous knowledge of it], nonetheless find rules [for solving it] through… — David Kahn Copy Share Image
![“The technique was at least moderately well known, for Ibn Khaldūn wrote in The Muqaddimah: “Occasionally, skillful secretaries, though not the first to invent a code [and with no previous knowledge of it], nonetheless find rules [for solving it] through combinations which they evolve for the…” quote by David Kahn](https://sms4smile.com/quotes/img-quotes/1d1/david-kahn-13896_programming_the-technique-was-at-least-moderately-we_657231.jpg)