Wool
George Mallory and Andrew Irvine wore state-of-the-art gear for the possibly first successful, yet ultimately fatal, ascent of Everest on 8ᵗʰ June 1924. Their recently discovered remains were found to be clothed in woollen long johns, silk shirts, woollen cardigans and tweed jacket, in seven layers underneath a windproof outer Burberry gabardine and plus-fours of tightly woven cotton1. They covered their extremities with hat and gloves, and hand-knitted wool socks inside their boots. These natural fibres provided equivalent insulation to modern polypropylene and down clothing for climbing Everest, if not for bivouacking near the summit, and they retained warmth even when damp. But they were heavy, and the more so when moist. Wool holds water, burdening the wearer.
Global wool production has almost halved since its 1990 peak, against a rising trend in the global stock of sheep2. Synthetic fleeces are much lighter to wear and cheaper to buy than woollens.
Wool continues to find favour, nevertheless, for hat and gloves and soft Merino inner layers. Even its wet weight has utility. Here is the Renaissance nobleman Michel de Montaigne,3 with a lesson that originates in 600 BCE Ionia yet retains currency to this day …
Has there ever been a more express case of subtle malice than that of the mule of Thales the philosopher? Laden with salt, it chanced to stumble when fording a river, so wetting the sacks; noticing that the salt dissolved and lightened its load, it never failed, whenever it could, to plunge fully loaded into a stream. Eventually its master discovered its trick and ordered it to be laden with wool. Finding its expectations deceived, it gave up that trick.