ephemeral

Ephemeral began as a precise measurement of time. The Greek ephēmeros meant ‘lasting a day,’ and when the word entered English in the late sixteenth century it described a fever that came and went within a single day. Over the following century it widened to describe anything brief: a passing fashion, a short-lived political alliance or a fleeting mood. The Roman emperor Marcus Aurelius, writing his Meditations in Greek, used the same root to remind himself how short-lived human affairs are.

Biology preserves the original sense most closely. Mayflies belong to the order Ephemeroptera, named for the brief life of the adults. After spending months or even years as aquatic nymphs, adult mayflies emerge with no working mouthparts, mate and die, usually within a day or two; in some species the adult female lives only minutes. Botanists speak of desert ephemerals, annual plants that germinate after rain, flower and set seed within a few weeks, then survive dry years as seeds. Hydrologists distinguish ephemeral streams, which flow only after rainfall, from intermittent and perennial ones.

The plural noun ephemera refers to printed and handwritten items never meant to last: tickets, posters, menus, leaflets and postcards. Collectors and historians value them because they record ordinary life in ways official documents do not. The Ephemera Society was founded in London in 1975 by Maurice Rickards, and major libraries now keep dedicated ephemera collections, from Victorian trade cards to concert flyers. For social historians, a single theater program or railway timetable can reveal prices, typefaces, advertising habits and leisure customs that no formal record preserved.

Many artistic traditions treat brevity as part of beauty. The Japanese aesthetic idea of mono no aware, an awareness of the passing of things, finds a familiar image in cherry blossoms, which usually fall within a week or two of opening. Tibetan Buddhist monks spend days creating sand mandalas and then sweep them away as a lesson in impermanence. The British artist Andy Goldsworthy makes sculptures from ice, leaves and stones that melt, scatter or wash away, documenting them only in photographs.

In the digital era the word has gained a new technical life. Snapchat, launched in 2011, built its early popularity on photos that disappeared after viewing, and Instagram Stories, introduced in 2016, vanish after 24 hours, returning the word almost exactly to its Greek meaning of a single day. Computer scientists also speak of ephemeral ports, ephemeral keys and ephemeral servers, all created for one task and discarded when it ends.