There are two fun facts about Shakespeare's King Lear that, one day, will make for excellent dinner party fodder if you don't know them already.

The first is that the Bard almost certainly wrote Lear during an outbreak of the plague, something locked-down Shakespeare scholars now suspect contributed towards its nihilism.

The second is that the premise of the play – three daughters, a rich man blind to the difference between sycophancy and honest affection – is based on an ancient fable called 'As Meat Loves Salt'.

I won't waste my word count telling you the tale, but suffice to say that by its end, the old man is left in no doubt as to salt's importance. This is true today – who would want a steak that hadn't been thoroughly seasoned before hitting the pan? – but was even more so in the 16th century, when salt was essential for preserving not just meat, but fish, vegetables and cheese for the winter months.

Like the man in the story, we take it for granted. There it sits, in our salt pigs, grinders and shakers, ready to be scattered liberally into pasta water and with caution into soups and sauces. Yet the reason this dazzling white crystal permeates the languages, stories and cuisines of the world is that without it, we wouldn't be here.

Whether it's as an agent for curing, fermenting, cooking or simply as an essential mineral regulating our bodies, "salt plays such an important part in our life," says chef and restaurateur Richard Corrigan, "that when you talk about the enjoyment of salt, you really have to talk about the enjoyment of living."

When you talk about the enjoyment of salt, you really have to talk about the enjoyment of living

By forcing us to fall back on our own kitchens and culinary capabilities, the pandemic and subsequent lockdowns have simultaneously opened a world of possibility – at least to those with the time and money to explore it.

We've honed our skills, cultivated new ones and experimented with different recipes and ingredients, but we have also – if the consistency with which we have searched for and cooked comfort food is anything to go by – been reminded of the joy of simple foods: pasta and cheese, bangers and mash, buttery scrambled eggs, fish pie, scotch eggs and chicken soup.

Fundamental to the flavour of all these dishes is seasoning – whether it's pepper's headline role in cacio e pepe or its more subtle presence in soups and sausages. Salt, too, runs through all of them, both as seasoning and as preservative. There is no cheese, Corrigan reminds me, without salt.

The chef and proprietor of Bentley's, Corrigan's and Daffodil Mulligan, Corrigan is speaking to me down the phone from his home in County Cavan, Ireland. Two counties along is Hannan Meats, the critically acclaimed butcher whose tender, succulent salt-aged meats are edible testimony to his words.

Corrigan

Thanks to the purifying, preserving qualities of Hannan's 12-foot wall of Himalayan rock salt, cuts of beef, lamb and pork can be aged for weeks, and taste all the better for it.

Hannan's signature method is the perfect realisation of an ancient practice which, while universal, is particularly common in the Northern hemisphere, where long, dark winters made preservation essential.

"Go back to the days we lived off the land, and you'll realise what salt meant for our own preservation," continues Corrigan, "particularly in January and February, when we were on the last of the root vegetables and there wasn't much left in the ground."

The importance of salt-based preservation not just of meat, but of fish and vegetables, too, was what lead Russian food writer Alissa Timoshkina to call her cookbook Salt & Time: Recipes from a Russian Kitchen.

"Everything I cooked had those elements. In winter in Russia the only homegrown vegetables you have are fermented," she explains.

"The more I thought about it, the more I realised the flavour that defined Russian food for me was the tang of fermentation," as in the fizz of fermented tomatoes, the sharpness of sauerkraut, the zing of silvery herrings steeped in oil and salt.

Salt & Time

Salt doesn't just enhance existing flavour through seasoning, she explains, but "through fermentation it actually creates complexity of flavour." The effect is such that pickles and krauts are effectively seasonings themselves, used to add colour and tang to soups, stews and braises.

Indeed, so ingrained is salt into Russian and Eastern European cuisine and culture, she explains, that "to say of your friend 'I have eaten a pound of salt with you' is to say 'We have been friends for a long time.'"

Of course, there's salt and there's salt. Himalayan pink salt – excavated, as you might expect, from the Himalayan foothills – has become something of a byword for foodie pretentiousness in recent years, but Hannan uses for its purity, and its ability (when combined with fans) to extract moisture and enhance meat's flavour.

In Britain, the main source used to be seawater; but when, in your local chippie, you grab a couple of salt sachets, or see 'salt' on the back of a ready meal, what you're seeing is manufactured (or PDV) salt, extracted from the land using a high-jet water pressure, sucked out in brine and heated in a vacuum chamber, "not slowly, as in the case of our sea salts, but instantly," says Fraser Ferguson of Salthouse & Peppermongers, a renowned supplier of artisanal salt and pepper, "which is why it's higher in sodium." Stick 15 artisanal salts in front of Ferguson and he would be able to identify at least 12, he says.

The latest addition to their range, Blackthorn Salt, is extracted from seawater in a large wooden tower filled with thorns on the west coast of Scotland. The water dribbles through the thorns and is evaporated by the sun and wind to create a strong brine, which is then heated up.

Maldon – a salt so prized that, like Nigella (who carries a small pack of it in her handbag) it's known by one name only – operates along similar principles, the vegetation of the Essex marshes serving as a natural filter and crystalliser so the saline content builds in their reservoirs.

Shovel of Maldon Salt

The prized Maldon salt

The salty water is heated slowly in large pans, and their resulting crystals are beautifully, iconically pyramidal – different in both look and taste to salt created through solar evaporation and rock salt.

"The higher the pyramid, the thinner the salt is – so when it hits the palate it melts, then as you start chewing you get another crunch," says Ferguson.

Though Blackthorn shares some similarities with Maldon, both are unique – and not just on account of the thorny tower or the marshes.

Even in Britain seawater salinity and minerality vary significantly along different stretches of coastline – so the sea salt which PR director-turned-salt maestro Jonathan Bird has been extracting since early last summer on Sark, an island off the coast of Guernsey, will taste different still.

"I love food, I love Sark, and I've always wanted to do something for this amazing island I grew up on," Bird tells me. It was whilst watching Samin Nostrat's brilliant Netflix series Salt Fat Acid Heat, that the idea of extracting salt came to him.

"I was so taken by how she described it. It seems crazy that across borders, ethnicities and even language we have this one small thing in common."

History of salt and pepper: the island of Sark

He's one of a growing number of small-scale salters to have set up in recent years, as salt joins the ranks of cheese and meat as a product in whose origins consumers are now interested, with food outlets and manufacturers following hot on their heels.

"We've seen a huge swing among manufactures from PDV salt to sea salt over the last 12 to 18 months. It's more sustainable, it has less sodium – it just looks better on the ingredients list," says Ferguson.

It's good news for our health – but it's even better news for the small, rural economies these salters are supporting though employment and supplier contracts. It's early days now, but Bird's dream is, like Maldon, to become one of Sark's major employers.

"Having relied on British tourism for so many years, it's become a victim of cheap package holidays to Spain and elsewhere. But when it comes to food, this island has so much potential."

It is possible, of course, to write about salt without mentioning pepper. Plenty have done so, and plenty more consider pepper to be an overused ingredient. "Salt is a flavour enhancer. Pepper is a spice," says chef Stephen Harris firmly.

Across borders, ethnicities and even language, we all have salt in common

While he reveres salt even to the extent of making his own for his Michelin-starred pub The Sportsman ("I can see the sea from here. Our nearest village is Seasalter, where they made salt for millennia. It made sense," he says simply) Harris uses pepper only on things like pommes anna, sprouts or swede, "where it actually works well."

I can see his point. As Jeremy Lee, the ebullient chef behind Quo Vadis in Soho points out, "If not used judiciously, pepper can be a real bully."

It can also be – as anyone who grew up in the days when shakers of ground pepper were ubiquitous – entirely flavourless: once ground, pepper loses its aromatics so quickly the pepper in those shakers is "little more than grey dust."

We could live without pepper, whereas we couldn't live without salt; it can only grow in certain parts of the world, where salt can be found almost anywhere.

And yet, when it comes to the history of European cuisine, pepper is just as pervasive and powerful – once used in place of gold, hence the term 'peppercorn rent'.

Food writer Christine McFadden calls it 'The Spice That Changed the World'. "Fortunes were built on pepper, bloody battles were fought over it, the New World discovered because of it," she writes in her book of that title.

Originating in Kerala in south west India, pepper and the story of its advance across the world is analogous to "the history of the spice trade as a whole." Alas, much of pepper's specific history remains shrouded.

"Even though pepper was certainly known as long ago as 1200 BC, it rarely gets a mention until much later, whereas spices such as frankincense, sandalwood and cinnamon crop up again and again," McFadden continues, speculating – as historians have done before her – that the reason pepper's progress is only sparsely recorded is the same reason it proved so popular. "It might well be because pepper lacked the heady sensuality of other spice."

It isn't romantic. It isn't colourful. "Some foods attract by sweetness, some by their appearance, but neither the pod nor the berry of pepper has anything to be said for it," complained Roman Philosopher Pliny the Elder.

Yet that's just it, says Jeremy Lee: "It doesn't impose, like juniper and coriander, but it brings out the flavour of everything, and adds vim, vigour and zip."

Pepper doesn't impose, but it brings out flavour and adds vim, vigour and zip

There's a reason for this, says Peter Schaebbicke, co-founder of a family run pepper farm in Kampot, Cambodia. By gently irritating the mouth, the heat generated by the chemical compound piperine "has this amazing ability to wake up your palate." For that reason, he argues, pepper is a flavour enhancer – not just a spice, as Harris asserts. "It engages your brain and enables you to taste flavours you couldn't taste before. That's why it took the world by storm."

History of salt and pepper: Smoked Eel Sandwich

With the spread of the Roman Empire, who "were the first [Europeans] to consistently use pepper in cooking," as McFadden writes, pepper, well, peppered the continent.

During the 16th and 17th centuries, pepper was "the world's most valuable export, accounting for 70% of the total spice trade." Inevitably as its ubiquity grew, so its lustre wore off – particularly with the influx of New World exoticisms like coffee, chocolate and tobacco. By the 20th century, says Schaebbicke, pepper was being produced in such quantity, "the quality came secondary."

Mercifully pepper is having a resurgence – again, thanks largely to the Italians. Having known only the peppery dust that sat in a shaker on the table, Corrigan's first encounter of a pepper mill was in his teens at an Italian restaurant: "Those huge grinders used to horrify me as a child!"

"Oh, we laughed uproariously at the Italians and their big pepper mills – but they were right," says Lee. The more pervasive the influence of Italian (as well as French and Indian) restaurants, the more we appreciated the merits of freshly cracked pepper, Schaebbicke claims, and the variety within it: the three harvests of black (dried unripe berries), red (dried ripe berries) and white (the seed of very ripe berries) peppers; the difference between, say, Keralan and Cambodian pepper; and the range of sizes (tellicherry and malabar refer not to varieties of peppercorn, but size.)

We laughed at the Italians and their big pepper grinders, but they were right

Like salt, pepper has had its trends: "In the 1800s, everyone loved the long peppercorn," notes Ferguson. More recently, it has been pink pepper (which is not actually a pepper, but a relative of the cashew nut) and now in pepper, as in honey, coffee and other commodified staples, the focus is turning to single-origin.

As Schaebbicke points out, "pepper is grown all over the subtropics – and many farmers don't know where their crop ends up." The majority goes to "massive warehouses, where it can spend four years before being packed and shipped" – so at the very least, buying direct from a specific cooperative or farm means better, fresher flavour.

Yet it is also about land and communities – "the entire eco-system," says Schaebbicke, who together with his brother in law and other like-minded individuals has helped regenerate Kampot after this historic pepper-growing region was decimated by Pol Pot in the 1970s. "The farmers we buy from are paid five times more than those selling in bulk."

It is sobering to think that a quick crack of black pepper over my softly scrambling eggs could echo as far as Cambodia. We think of the eggs, and the chickens that bore them; of the butter and cheese, and the cows and people who made them; but we rarely stop to consider our sources of salt or spice.

Speaking to these chefs, salters and suppliers, I feel like the man of that fable: not in my egotism or venal daughters, but in my blindness to salt and pepper's inestimable value. They are so small, so seemingly simple – and yet in their cultivation, flavour and history they encapsulate so much of what it means to be human: for worse, but also for better, if carefully used and responsibly sourced.

Here endeth the pep-talk; now go forth, and be the salt of the earth...