Summer's arrival in the northern hemisphere brings with it a dilemma that plagues every office worker.
What does a casual dress code mean in practice?
The happy medium between looking like Kim Kardashian or Hagrid the giant is hard to pin down.
Goldman Sachs has just implemented a "flexible dress code"
although the executive memo noted gnomically that "casual dress is not appropriate every day".
Besuited corporate clients might not take kindly to investment-banking advice offered by someone wearing a tank top and ripped jeans.
It makes sense that banking would be one of the last bastions to fall to the advance of casual workwear.
You want the people who look after your money to appear sober and respectable.
For similar reasons, bank headquarters have deliberately been built in a grandiose style to emphasise the institution's financial solidity and historical roots.
Depositors might hesitate about handing over their savings to people working under a railway arch.
For men, the move to casual dress seems entirely positive.
Few people will mourn the demise of the tie, a functionally useless garment that constricted male necks for a century.
The tie's origins date back to the 17th century, when mercenaries hired by Louis XIII of France wore a form of cravat.
The modern version of the tie emerged in the 1920s and was popularised by Britain's Edward VIII
who, when not flirting with the Nazis, developed the Windsor knot. It became standard office wear for the next six decades.
In the 1990s ties started to go out of fashion because technology titans and hedge-fund managers refused to wear them—
and were rich enough to ignore social convention. Once, when Mark Zuckerberg, the founder of Facebook,
was to meet a venture capitalist, he turned up wearing his pyjamas.
The jacket, by contrast, is a much more useful garment, replete with pockets to house wallets,
spectacle cases and travel passes (or, these days, mobile phones).
So the default work garb for men, when meeting clients, is jacket, open-necked shirt and dark trousers (denim excluded).
On days without meetings, men can slob out in t-shirts (though not too garish) and jeans, and no one will think the worse of them.
Arriving in shorts or without socks is another matter entirely.