LONDON • About 2004, somewhere between the Balenciaga Lariat and the Chloe Paddington, the fashion world reached its peak with the It bag.
It is funny to think about, now that the handbag market is all about cross-body comfort and accessible price tags, the obsessive worship once directed at bonkers-looking handbags.
The status of the It bag soared sky high, entirely unmoored from the practical notion of a handbag as a vessel for stuff.
The tiny Fendi Baguette - "foolish, a treat, anti-functional", according to Silvia Fendi, who designed it - became almost a character in its own right on the Sex And The City movie.
Every decade has an It. There will always be a cult item that people invest with undeserved meaning and obsess over until they drive the price up.
And if you think the It bag craze was ridiculous, consider the fact that this decade's It are the workout leggings.
Performance leggings - to give them their proper, trophy title - are the new It bags.
Net-A-Sporter - the booming fitness spin-off from the grand dame of Internet shopping - has Fendi stretch-jersey leggings for £300 (S$575) and no fewer than seven other brands, whose leggings cost more than £100 a pair.
Just as the demand for and hoopla around handbags drove the expansion of luxury shopping, so the mania for performance leggings is fuelling the expansion of athleisure.
The word "athleisure" did not exist until 2014, but it is now used to describe a market for worn-to-be- seen workout clothes that was worth £6.4 billion last year in Britain alone, a figure expected to grow to more than £8 billion by 2019.
Trainers are still the prime product in this category, but leggings come a close second.
Mr Mark Parker, chief executive officer of Nike, has described leggings as "the new denim".
There is certainly no shortage of glamour: Actress Kate Hudson has her own fitness brand, Fabletics, while Under Armour, in their bid to expand into the lucrative female market, has recruited model Gisele Bundchen and ballerina Misty Copeland as brand ambassadors.
It is leggings that people have zeroed in on, rather than vest-tops or sweatshirts, because these tight, snazzy leggings are the part of fitness wear that has changed the most.
The bottom half of your look is what makes it current or not. You can wear the grey marl Gap tank top you bought 10 years ago, but you will be laughed out of barre class for wearing tracksuit bottoms.
The graphic prints and diagonal stripes that characterise top-of- the-range leggings are as instantly recognisable and, as tribal as the Nike swoosh once was.
So important is design that cult brand Lululemon sued Calvin Klein for allegedly copying its Astro yoga pants.
Fitness now is see-and-be-seen, with upscale athleisure marketed as all-day weekend wear.
The actual exercise is increasingly social, too. Running is no longer just a solo affair, but structured around workplace lunchtime runs, 10km winter races and half-marathons
Going to the gym on your own is over: It is all about pilates, spinning, Barry's Bootcamp or yoga.
Look at a page of paparazzi photos this year and you will see many more Lululemon leggings than mink coats.
The looking-fly-as-you-exit-the- gym look is as aspirational now as walking into San Lorenzo with your special-order Balenciaga once was.