It was a love affair that began in Khartoum - as soon as I felt the pale, blue, Egyptian cotton soft against my fingers. I bought a length of it and took it to one of the tailors who operated an old black and gold Singer sewing machine from his pavement pitch. "Could you make a djellabiya from this?" I asked. The tailor put his hand on his heart and inclined his head. "How tall is your husband?" he asked, for the djellabiya is a male garment. "The same size as me," I lied. (Forgive me, Allah.) The measurements were taken with the tape held a respectful distance from my shoulders, arms and legs. Two days later, I had a garment fit for Belqeez herself: a long, flowing gown with loose, wide sleeves, perfectly tailored, finished with white piping. I lounged in it, slept in it, danced in it, made love and breakfast in it and eventually - because we must not become attached to earthly things - I parted with it. By then, it was worn and torn and anyway, Khartoum has changed.
The love affair continues, however, for once you have known the cool sweetness of pure cotton, nothing less will suffice. Tonight, I will sleep between freshly laundered, cream, Egyptian, cotton sheets, the pillow cases starched and bordered in indigo. And one day, when I am very rich, I will alternate the cotton with pure, Irish, linen sheets.
While we may be what we eat, we are also affected by what we wear. Judith Hoad, in her excellent book Healing with Herbs, notes that of natural fibres, animal fibres (wool, silk and feathers) are the warmest - hence the duck-down in our duvets - whereas vegetable fibres (linen and cotton) are the most cool. Man-made fibres, however, trap body sweat, which is why we get restless and uncomfortable with sheets that have polyester in them and this is why the very best hotels use only 100 per cent cotton sheets on their beds. If you encounter anything less, walk on.
There are lots of different cottons, including Asian cotton from India and Sea Island cotton from the now volcano-stricken Caribbean island of Montserrat, but the beauty of Egyptian cotton is that it is made with a long staple thread which gives the cloth its lustrous gleam.
Micheal Howard, head of the bed-linen department in Dublin's Arnotts and a textile guru, says that Egyptian cotton is also extremely durable, due to the number of threads per inch. A good quality cotton will have maybe 150 while the best will have 200. It is the thread per inch ratio that prevents the cloth from piling - that distasteful habit which man-made fibres have of forming small clots of itchy thread on the surface of the sheet.
Cotton is tremendously easy to care for: you can put it in the washing machine, though not in a hot wash as the fibres can shrink. The rule of care for 100 per cent cotton should be: warm wash, don't tumble-dry and iron while still damp. At Brown Thomas's Bottom Drawer, Lisa Duffin stocks the very best of Italian bed sheets: "They're made of Egyptian cotton but designed in Italy because the Italians are great designers." And you can see that in the way the smooth, shimmering sheets are finished with a fine cord, blue or white to match the overall design.
At Bottom Drawer too, they stock Irish linen, which comes mostly from Lamonts of Ballymena. "We started in 1830," says David Lamont, "when the family was delivering flax by horse and cart to cottage weavers. Then it would be collected and brought to the Linenhall in Belfast to be finished." In those days, the bleached cloth was flattened by beams big as railways sleepers which smoothed the linen and gave it its sheen. Pure, white, linen sheets are, of course, classics and if you're going to buy any, they've got to be Irish. They are costly on account of the complicated process but worth every penny because linen, like diamonds, is forever.
Our discerning visitors from Germany and the US know this, which makes them the biggest buyers of Irish linen, according to both Arnotts and Bottom Drawer.
You can get a less expensive linen, manufactured in France and dyed to strong colours such as blue and wine or navy and white gingham. Finished with buttons and bordered with natural-coloured linen, the French bedding is fresh and attractive to look at and quite a contrast to Irish linen which always comes in its natural colour. The big problem, however, is its care. While linen actually improves the more it is washed - it will go in a washing machine with no danger of shrinkage - it's the ironing that may prove daunting. There have got to be solutions, of course. "Bono's wife Ali was in here recently buying linen sheets," says Lisa Duffin, "and I doubt if she's going to stand there all day, ironing them."
Some people, however, find it calming to dash away with the smoothing iron. If you're one of them, the form is to iron the sheets while damp, first on the wrong side to remove the creases and then on the right side to bring up the sheen. Alternatively, you could send them to a good laundry, if you can still find one.
In Dublin, the Donnybrook Laundry (012838388) specialises in hand-finished linen, both for bed and table use. You can take your laundry directly to them or you can find a dry-cleaners which uses them. But be warned: I paid a dry cleaner £8 to have a cotton sheet, duvet cover and two pillow cases laundered, starched, pressed and folded.
Had I gone to the laundry direct, it would have cost around £5. The best method of storing linen, by the way, is to wrap it in brown paper and put in the hot press.
And while we're on the subject of linen, Bottom Drawer does a magnificent invigorating bath sheet, stone coloured, in linen and cotton mix. To toga yourself up in one these is the final, pre-bed luxury.
Prices: Kingsize luxury-finish cotton sheets: £49.95 a pair. Irish linen sheets: £299 a pair, both from Arnotts of Henry Street, Dublin. Overseas readers can browse the web for lots more linen on www.irelandathome.ie. In Bottom Drawer, in Dublin's Brown Thomas, a set of French bed-linen (double sheet, duvet cover and two pillow cases) costs £235 while the same in Lamont linen costs £495. The Lamont linen and cotton bath sheet is £29.99. Lamonts also supply Roches Stores.