We're in danger of disappearing under a froth of bubbles. There's the 'private-equity bubble', the 'housing bubble' and the return of the 'dot.com bubble'. This venerable term was first applied to crazed speculation in 1721, when Jonathan Swift, of Gulliver's Travels fame, used it about the South Sea Company, whose shares rose from £100 to £1,000 and fell back again within a year. Swift borrowed an earlier idiom for anything fragile, insubstantial or deceptive: Shakespeare talks of 'the bubble Reputation'. In the late 19th century, US economists used the term for any unsustainable price-rise. It is first recorded in the 14th century as a verb, perhaps mimicking the sound of a bubble forming and bursting. For a while, to 'bubble' someone was to cheat them, and a 'bubble' was someone thus cheated. Today, a 'bubble' is likely to be a Greek, a derogatory piece of rhyming slang arising from 'bubble-and-squeak', a noisily fried dish first enjoyed in 1772: comfort-food for anyone whose bubble has burst.