For most people whose only involvement in fashion is casual - the odd trip to a mall to stock up on T-shirts and shoes - it is a world for which the word "fickle" might have been invented.
The boot-cut jeans you thought really suited you are now unavailable because everyone's producing skinnies, which don't do anything for you. The investment you made in a really good jacket, on the advice of a fashion magazine that told you it would look good for a decade, is wasted because suddenly the shoulders seem strangely wide, the waist too defined, the lapels too extravagant. Why? Because fashion told you so.
It's how, necessarily, our clothes are able to meet the demands of the modern world, but that approach is to overlook the meaning and the craftsmanship that is at the heart of fashion.
The cultural implications of even the anti-fashion looks - the hoodie, the preppy, the corporate - make this a constantly fascinating subject. And the art of creating the embroideries of Pakistan, the prints of Japanese kimonos or the rigid structure of British model millinery transform certain elements of clothing into artefacts that will never date. My 1920s opera coat, for example, is not in fashion - but then it's not out of fashion either, and never will be because it's a piece that has stood the test of time. That's part of the appeal of vintage fashion.
In fact, this is something that absorbs many fashion designers far more than the relentless swing of the trend pendulum. They are often compulsive collectors of vintage pieces - Victorian lace, 1930s buttons, 1950s hats - and antique costumes, whether as inspiration for their own designs or simply as extraordinary objects in themselves. John Galliano, in his heyday, was known to frequent the markets of Camden Lock (strangely to the disgruntlement of many of the traders, who grumbled that the vintage pieces at their stalls would be seen on the catwalk two years thence).
When I met the Emirati shoe designer Sultan Al Darmaki at his home in Richmond, London, last week to talk to him about the Victoria & Albert Museum's acquisition of one of his designs for their permanent collection, this was an aspect of fashion that occurred to me again.
It wasn't just because Darmaki's shoes are now part of one of the world's great fashion collections, there for posterity, to be studied by future generations as their current holdings are studied by today's designers. It was because on his wall was the most extraordinary 18th-century Ottoman robe, spread out on a canvas so that as much detail as possible was visible. It was made in a colourful ikat silk - a complex, painstaking weave that has huge amounts of meaning and history across the east and Central Asia, from Turkey to Japan - and in it I saw the inspiration for his next colourful collection of shoes. On another wall was a tiny, intricately embroidered bolero jacket, while his chaise longue was upholstered by a pair of Beiruti designers using a patchwork of vintage Middle Eastern fabrics.
Each of those pieces had a story to tell, and the pre-industrial techniques that were used rendered them more unique and precious than 50 Topshop frocks (if far less wearable and useful). The fact that they had been preserved for so long was a reminder of the great value that we once placed on clothes and craft, before we demanded the disposable.
A few days later, I visited an exhibition of the Staffordshire Hoard, the largest collection of Anglo-Saxon treasure ever unearthed in Britain. Around 1,400 years old, it consists almost entirely of weaponry, and what weaponry it was: gold sword pommels, exquisite garnet cloisonné panels and filigree swirls so minuscule that even with a magnifying glass it is hard to comprehend the detail.
How exactly these pieces were made remains a mystery, baffling modern jewellers. What they show, though, is that while no written record of their owners remains, these pieces of fine craftsmanship can tell us an extraordinary amount about who made and wielded them, the culture in which they existed and the values by which the wearers lived.
Fashion, in other words, might be ephemeral when we're shopping on the high street, but those pieces that are timeless and yet utterly of their time - the Darmaki shoe, the Stephen Jones hat, the Anglo-Saxon sword pommel, the Roman brooch, the ancient glass beads - show that costume offers an unrivalled means to interpret life and history.
Darmaki spoke of the inspiration he took from his grandmother's burqa when he designed his Lydia shoe, and there is still an opportunity to record the history of costume in the Emirates from living sources. I hope that project is being undertaken by some enterprising and fashion-loving soul.