The first synthetic purple dye was invented in 1856.
(As with ice cream though, take it as read that the Chinese actually got there first).
The word purple was at its zenith in 'British English' books in 1900.
The Americans however hit peak purple in 1870, the up and coming super power was far ahead of the British Empire!
Purple was a big deal, as beforehand it was expensive to produce, and all of a sudden anyone could go purple with cheap synthetic dyes.
We take purple for granted nowadays, and can afford to be condescending at our ancestor's purple obsession.
The fads just keep coming however.
Peak 'puzzled' hits America after both world wars.
I am constantly puzzled, but it clearly waxes and wanes amongst the nation's authors.
We chuckle at purple obsessions; scratch our heads in response to undulating puzzlement; but economics is even more inconstant - flirting with ideas on a yearly or even monthly basis.
Econo-physics comes in and out of vogue every once in a while.
Partly because the ideas seem so pure, but mostly it's down to financiers and economists trying to cling onto something more permanent.
Financiers should make more imaginative analogies. Perhaps to food, history or music - but the appeal of permanence is too strong.
My old macroeconomics professor used to liken economics to religion and name checked old saints all the time.
Keynesian-ism was 'mana from heaven' for example. Another way to desperately clutch onto something permanent.
As a past editor of game theory monthly, he knew as well as anyone else that Maxwell's equations will outlive Biblical references, nevertheless his religion made for more colourful lectures.
(Hopefully Emanuel Derman still references fruit salad whenever he explains the Vanna Volga method!)
Just as Coca-Cola juxtaposes cancerous murk juice and energetic people - financiers market their funds by referencing truly permanent ideas.
Think about that.
Fruit salad anybody?