These days it’s a fairly low-level hacker exploit to open and read emails intended for somebody else. That sort of thing used to be a bit more difficult, at least in terms of physical skills.
The way you’d protect a document a couple millennia ago was to apply a seal, probably made of molten wax or something similar, then while the wax was still pliable, you’d press some unique, recognizable pattern into it — a ring with a fancy pattern, for example. To open the document you’d have to “break the seal” — and then everybody would know what you did just by looking at the document.
To read documents intended for somebody else without being detected, you’d have to replicate the wax seal with its imprinted pattern. The obvious way to do that would be to use the existing wax to make a mold, then recreate the pattern in a new blob of soft wax. People being people, that’s exactly what they did. But the stuff is soft wax, so you couldn’t use anything hot to make your mold.
In the first century BCE a Greek named Lucian even explained how it was done. You’d make the mold out of something called “collyrium.” This was some sort of modeling-clay-like stuff made out of pitch, bitumen, “pounded glass” (not sure what that part was for), wax, and “mastic,” which is resin (basically sap) from a mastic tree, a small tree common around the Mediterranean.
“Colllyrium” in the original Greek was “kollurion,” which is from the word “kollura,” and oddly enough, a “kollura” is a dinner roll. Possibly Lucian thought the mold-making stuff was similar to bread dough — which, now that I think of it, you might be able to use instead.
Relatively soon after Lucian published the the Hacker’s Digest of ancient Greece, the word “collyrium” acquired another meaning. The Romans started using it to mean any kind of medicine or salve that was made in a sort of gummy cake. You might rub the stuff on your sore elbow or knee, or you might dissolve some of it in water to apply. Or you might even drink the mixture. Medicine being somewhat hit-and-miss in those days, the “collyrium” was probably made of some of the same stuff Lucian mentioned. Hopefully not the pounded glass, if you were going to drink it.
There’s yet another meaning for “collyrium” though — even two thousand years ago people wore makeup, and in particular dark eye shadow. Dark eye shadow came to be called “collyrium” too. Two of the meanings sort of merged, and “collyrium” came to mean a medicated salve for your eyes. Another case for replacing the “pounded glass” with some other ingredient.
The “medicine for eyes” meaning of “collyrium” turned out to be the one that stuck — to the extent that Ralph Waldo Emerson’s readers knew exactly what he meant, in 1850, when he wrote that “Great men are thus a collyrium to clear our eyes from egotism.”
“Collyrium” is not an entirely forgotten word, but it’s now extremely rare. You might run into it very occasionally, but for the most part it’s so hard to find you’ll get eyestrain looking for it. Luckily, if you do hurt your eyes, now you know you can just apply some collyrium.
