leuga

The league is one of the oldest distance units in Western Europe, and its origin is Celtic. Leuga (or leuca) was a Gaulish word that the Romans adopted to describe a unit of distance used in Gaul, equivalent to about 1,500 Roman paces — roughly 2.2 kilometres. Roman milestones in Gaul used the leuga instead of the milia passuum. The Gauls measured distance differently from the Romans, and Rome, for once, deferred.

After Rome fell, the league evolved independently in every European language. The Spanish legua was about 4.2 kilometres. The French lieue was about 4.4 kilometres. The English league settled at approximately three statute miles, or about 4.8 kilometres. The nautical league, used at sea, was three nautical miles — about 5.6 kilometres. No two countries agreed on the league's length, which is why it eventually fell out of official use.

Jules Verne's 1870 novel Vingt mille lieues sous les mers is routinely misread. The title means twenty thousand leagues traveled under the sea, not twenty thousand leagues deep. Captain Nemo's submarine travels sixty thousand miles beneath the ocean surface — a horizontal distance. The sea is nowhere near twenty thousand leagues deep. Even Verne's title, the most famous use of the word in modern culture, is misunderstood.

The league disappeared from legal measurement systems by the nineteenth century, replaced by miles and then kilometres. It survives in literature, in Tolkien and Verne, and in the idiom 'out of my league,' which originally described distance, not social class. The oldest Celtic road measurement became a metaphor for unreachable things.