A Greek poetic inscription was found on a sundial in the city of Herculaneum, which, like Pompeii, was buried by Vesuvius in AD 79. It is older than that, however, and was widely enough known and well enough respected to have found its way into an ancient collection of such poems called Palatine Anthology (the “A.P.” of my title).
ἓξ ὧραι μόχθοις ἱκανώταται⋅ αἱ δὲ μετ’ αὐτὰς
γράμμασι δεικνύμεναι ΖΗΘΙ λέγουσι βροτοῖς.
Six hours are quite sufficient for work. But the ones after those,
which read ΖΗΘΙ with their letters, say “enjoy life” to mankind.
There’s a joke here, and to get it you need to know
(1) that Greek letters double as numbers:
α = 1
β = 2
γ = 3
δ = 4
ε = 5
ϝ = 6
ζ = Ζ = 7
η = Η = 8
θ = Θ = 9
ι = Ι = 10
(2) that there were 12 hours in the daytime, numbered 1-12, spanning dawn to dusk.
(3) that Ζ, Η, Θ, and Ι are the afternoon siesta hours 7-10 (i.e., 1:00-4:00, approximately).
(4) that ΖΗΘΙ is the Greek imperative meaning “live!,” with a sense of “live well!”
The poem engineers a witty perceptual shift. It begins with the assertion that 6 hours are enough for work, and looks at first as though it merely goes on to list the hours that follow by their letter equivalents. The words γράμμασι δεικνύμεναι “designated by their letters” prompt us to this humdrum interpretation. But once you get past the numbers, the word λέγουσι (“they speak/say”) does all the work by making you now see that the numbers are “speaking” a word: the numbers not only designate the hours for enjoying life, but when taken together as a word they order you to!
The illustration is merely to relieve a wordy essay with some authentic ancient Greek characters in a papyrus letter preserved at The Metropolitan Museum in New York, which has released the image to the public domain through Wikimedia Commons.