‘Gresham’s Law,’ said my husband unkindly, possessing himself of the zapper and hopping between channels quite unnecessarily. I had just asked him the difference between an irrational number and a transcendental number.
‘Gresham’s Law’ is his shorthand for: ‘Something you don’t understand.’ It is true that in the past every time I have asked, ‘What does Gresham’s Law mean?’ my husband has said, ‘Ah, you don’t understand.’ That is surely what I had admitted by asking the question in the first place. I knew Gresham’s Law said: ‘Bad money drives out good.’ But what that meant or how it could happen were blanks to me. I need only have looked up the 17th definition of the word law in the Oxford English Dictionary.
Gresham’s Law is ‘the principle, involved in Sir Thomas Gresham’s letter to Queen Elizabeth in 1558, that “bad money drives out good”, i.e., that when debased money is current in the same country with coins of full legal weight and fineness, the latter will tend to be exported, leaving the inferior money as the only circulating medium.’
I see now. It’s by exportation that the good money is driven out. Gresham was always bringing home from abroad, as fine presents for useful people, things like sausages, tongues and paving-stones. Edward VI was said to have been squared by a pair of Spanish silk stockings. Perhaps the sausages, tongues, paving-stones and silk stockings left in circulation abroad were correspondingly impoverished, but it did him no harm. He seems to have been something of a crook, and his great achievement, the wonderful edifice of the Royal Exchange, was burnt down in 1666.
In language Gresham’s Law applies too. A reader has just written to complain about ‘the 1700s’, ‘the 1800s’ and so on being used to mean ‘the 18th century’ or ‘the 19th century’. It is true. It has happened in The Spectator, and happens on the BBC all the time. To us, the 1700s means the years between 1700 and 1710. But orthodox English speakers are increasingly unable to use the word 1700s lest readers think the whole 18th century is meant. It is the same story as the destruction of the former meaning of billion (a million million) by the new meaning (a thousand million). The bad meaning drives out the good. It is not by export, indeed it is often by importing American meanings.
Now I shall go and look up irrational number and transcendental number before my husband starts using them as shorthand instead of Gresham’s Law.