Envelopes are one of those banal objects of everyday life we seldom think much about. They are, however, an ancient  — and at one time controversial  —  privacy technology.

Envelopes render their contents secret. Today, once sealed inside a simple paper envelope, all kinds of messages  —  bills, birthday greetings, college acceptances and rejections  — are safe from prying eyes as they travel across town or continents to the intended recipient. In the United States, it is a federal crime to open someone else’s mail without permission, and, for the most part, government officials need a warrant to do so.

Before writing was invented, the only way to send a message without delivering it yourself was via a messenger who would memorize and repeat it — a person who would of necessity be privy to the contents. Cuneiform script was invented in Mesopotamia around 3200 B.C.E. and by the time of King Sargon of Akkad (about 2334–2279 B.C.E), people were writing personal letters  — and sealing their inscribed tablets inside clay envelopes. Unlike the oral message, the contents of such letters could be kept private, known only to the writer and recipient¹.

Letter writing was popular among the ancient inhabitants of Mesopotamia. Thousands of cuneiform letter tablets have been found, including many encased in privacy ensuring envelopes (though remains of envelopes are less common, unsurprising given that they need to be broken to get to the message). There are records of such correspondence between kings to their representatives in far-flung outposts, and also of more modest exchanges between business partners, friends and family members.

But in ancient Greece, although writing was used extensively for record-keeping and inscriptions, personal letters were relatively uncommon. For the Greeks, the privacy that letters conferred rendered them suspicious. Why seek secrecy unless one is plotting or lying? Several of Euripides’ plays have plots featuring deceptive letters and claims of forged or false letters were not uncommon in orators’ speeches. Both Herodotus and Thucydides recount intrigues and betrayals enabled by deceitful letters. Clearly, although the Greeks associated letters with deceit and manipulation, they still at times wrote them.

Why was letter writing esteemed in the Mesopotamian civilizations, yet distrusted by the Greeks? One explanation is their differing regard for the public sphere. For the Greeks, and especially the citizens of democratic city state, the public sphere of the agora was idealized. One’s business, it was felt, should be carried out in the open. Private letters were a threat to the democratic process; even when generals and ambassadors wrote letters reporting news from far away, they were not private: the messages were read publicly to the assembly. In contrast, other ancient civilizations were ruled by powerful kings and emperors, often believed to be emissaries or descendants of the gods; in such societies, even if public life was cherished, there was no equivalent near-compulsory participation in open discussion and debate².

Today, physical mail is becoming obsolete as communication moves online; the secrets that most envelopes in our junk-mail-dominated postal delivery hold are about magic weight-loss pills and lotteries for cruises.

Yet the concept of the envelope lives on, not only as an anachronistic interface metaphor (like carbon copies), but more importantly, as a model and precedent for shaping internet privacy law. It is useful, then, to look at the history of the mixed reception for envelope and the privacy it provides, and to keep in mind that privacy and public life need to be balanced. The Greek insistence on public communication was not aimed at stifling dissent but at encouraging debate. Privacy is not an inherent good but is rather a protection. Where conformity is enforced it is necessary for freedom, but where diverse opinions and divergences can thrive, the cost of privacy — including the potential for manipulation and deception  — may be prohibitive.

Judith Donath synthesizes knowledge from urban design, evolutionary biology and cognitive science to design innovative interfaces for on-line communities and virtual identities. She is the author of The Social Machine: Designs for Living Online (MIT Press, 2014) Currently, she is an advisor at Harvard’s Berkman Klein Center and is working on a book about technology, trust and deception. She received her doctoral and master’s degrees in Media Arts and Sciences from MIT and her bachelor’s degree in History from Yale University. This essay was originally published by Medium.

¹ And the scribe who, in many cases, was hired to write the letter. Though scribes, like messengers, would be privy to messages, concerns about privacy would be less. A scribe would not necessarily know the identity of the recipient. More fundamentally, being a scribe, even one for hire in the marketplace, was a highly respected position that required years of education and one that depended on maintaining a reputation for honesty and discretion. [return]

² The envelopes of ancient Assyrian traders did indeed at times conceal secret plans, such as instructions on how to smuggle goods to escape paying taxes.