Beware of this message

Generals and soldiers must pass messages up and down the chain of command in secret to avoid interception by the enemy. The same applies to cities. Writing in the 1600s, the English natural philosopher (and proto-semiotician) John Wilkins (1614-1672) affirmed that

“there are certain ways to discourse with a friend, though he were in a close dungeon, in a besieged city, or a hundred miles off” (4).

Wilkins recounted numerous methods of sending messages in secret, and included several examples of the kinds of short messages delivered by citizens and leaders under siege:

“The pestilence doth still increase amongst us we shall not be able to hold out the siege without fresh and speedy supply” (69).

Epidemics and starvation were amongst the afflictions that beset a besieged city, and required secret communications.

Secret obsessions

I’m reading Katherine Ellison’s book A Cultural History of Early Modern English Cryptography Manuals. She recounts the 400 year history of secret messaging as a necessity, a hobby, and an obsession. Though secret writing dates to the dawn of language, by other accounts, people’s interest in it is a product of the age of print. See post: The immoveable typist. Wilkins’ book is a prime example of one of these early cryptography manuals. Ellison writes:

“Cryptography is clearly, in Wilkins’s description of his motivation at least, a promising solution for loneliness and survival in a disconnected world of local and global conflict” (6).

I’ve not yet heard of people resorting to the study of cryptography as a means to keeping themselves occupied during the pandemic lockdown, though solving puzzles, playing video games, and sending messages are. Now the privacy needs of digital communications are of course met by automated encryption invisible to the user.

This is not a message

There’s a complete facsimile version of Wilkins’ Mercury at Google books and elsewhere. The full title on the book cover is Mercury: Or The Secret and Swift Messenger showing how a Man may with Privacy and Speed communicate his Thoughts to a Friend at any Distance.

The most cunning methods of passing messages are those that conceal to a potential interceptor that there is even a message in play. One method involves an innocuous knotted piece of string. When unfurled and zigzagged across a wooden template guided by side notches, the otherwise random knots line up against the letters of the alphabet to reveal the secret message.

As far as I can make out, this one says, “beware of this bearr who is sent a rasapy over you.” Allowing for my misreading of Old English typography, I think it should read “beware of this bearer who is sent to spy over you.”

This is not a haircut

The current lack of hair salons drew me to another method recounted, though not recommended, by Wilkins. The sender would shave the head of a young servant, then write something on the servant’s scalp. When the hair had grown back the servant would be dispatched to the recipient, who would then shave the servant’s head to reveal the message. So, not all messaging techniques are instantaneous. Wilkins doesn’t provide an example of the kind of message that would be so conveyed. I would be pleased if it said something like “don’t ask me what I’m doing for the holidays.”

The Handbook of Semiotics lists Wilkins amongst the progenitors of modern semiotics. Volumes 1 and 2 of The Essential Peirce mention neither Wilkins nor cryptography, but according to an account by Yvan Beaulieu, Peirce developed a detailed system of cryptographic encoding that anticipated the binary computer.


  • Beaulieu, Yvan. 2008. Peirce’s contribution to American cryptography. Transactions of the Charles S. Peirce Society, (44) 2, 263-287.
  • Ellison, Katherine. 2017. A Cultural History of Early Modern English Cryptography Manuals. London: Routledge
  • Nöth, Winfried. 1990. Handbook of Semiotics. Bloomington IN: Indiana University Press
  • Peirce, Charles Sanders. 1976. The New Elements of Mathematics: Volume 1 Arithmetic. The Hague: Mouton
  • Wilkins, John. 1641. Mercury: Or The Secret and Swift Messenger. London: I. Norton for John Maynard and Timothy Wilkins


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