"Take cokkes of kellyng; cut hem smalle. Do hit yn a brothe of fresch fysch or of fresh salmon; boyle hem well. Put to mylke and draw a lyour of bredde to hem with saundres, safferyn and sugure and poudyr of pepyr. Serve hit forth, and othyr fysch amonge: turbut, pyke, saumon, chopped and hewn. Sesyn hem with venyger and salt."
Cockles of codling or "kellyng", they called it. Recorded in an anonymous manuscript kept at Yale University, this Middle English recipe is believed to date from the 15th century and those early, feverish years of the Great Cod Rush. And feverish they were. This fish is a perfect food source, built to survive. Omnivorous, its greed is such that it will consume anything in the shallowest of waters. For centuries, it fuelled entire economies. Our geographical location means Ireland has ever been only on the fringes of the fishery. But it was the mighty Basques who found the richest grounds, and the salt to go with it. Only the Catholic Church spoiled it all slightly, by linking Friday fish-eating with sexual abstinence. Now there's an interesting conservation idea for EU Fisheries Commissioner, Emma Bonino . . .
Mark Kurlansky, author of a new "biography" on the fish, wonders whether this association with abstinence explains the sexual connotation salt cod carries in several languages. Although unsure of the answer, he ponders that apart from codpiece, an indispensable 16th-century fashion item, there is "morue" (cod) in French, which is slang for a prostitute. The English-speaking Caribbean reference to "saltfish" is even more pointed - but let's not put you off your dinner altogether.
With shades of Dava Sobel's Longitude, and echoes of the "Newfie" seascape of E. Annie Proulx, the New York-based foodwriter has taken a lateral approach to a "fish that changed the world". Comprising almost 80 per cent protein, there is no waste to cod. Icelanders (who still stuff cod stomachs with cod liver and eat them like sausages) used to consume the milt, the sperm and the whey. They would roast the skin and serve it with butter to children, while softening the bones in sour milk for yet another dish. As for remaining organs and bones, they made excellent fertilizer.
It is in the Newfoundland fishing town of Petty Harbour, off the Grand Banks, that Kurlansky's tale begins. Here, fifth-generation "Newfies" speak with broad Irish accents, and allow a river to divide them by religious persuasion. But this community of almost 1,000 is in deep trauma not because of religious differences, but because its livelihood has been snatched away with the closure of the Grand Banks cod fishery.
The future of the fish and the coastal communities dependent on it are inexectricably intertwined, have been for generations - not just in Newfoundland, but all around the northern hemisphere.
The nightmare of Petty Harbour is that it is at the wrong end of a 1,000-year fishing spree.
Ironically, the community is famous for banning certain fishing techniques in coastal waters from the late 1940s, and sticking to hand-lines and traps. This was no idealistic environmentalism, but a pragmatic management measure. With 125 fishermen working one small cove, trawling was not a practical option. Kurlansky describes how the inshore skippers now apply their skills to tagging programmes to conserve a dying stock, and joke that they are not real fishermen anymore. "Ooh, I think I am going to be seasick!" one fisherman jokes as his small boat hits a slight swell. In the course of his book, Kurlansky chronicles the cod "spree", sparked off by the Basques, north-west Spaniards who pursued a fish not particular to their waters: far from home, they used salt to keep it fresh in their holds. They were not the first to cure the "bacalao", he says. Norsemen, who had established plans for processing dried cod in Iceland and Norway, depended on such supplies for their five expeditions to the Americas between 985 and 1011.
Clearly, if the Basque fleets had had their way, America would not have been officially "discovered", and they would not have had to share the rich, north-east Atlantic grounds.
The biography of cod bears has historical anecdotes, references and literary allusions, and has a hard, political edge with its requiem for the Grand Banks, and a potted history of the man who revolutionised north Atlantic fishing - Clarence Birdseye.
Turning to today, Kurlansky looks at the question of whether the Spaniards are, as is so widely perceived, the pirates of European waters. Perhaps, he says, but points out that the giant bacalao companies have closed and the boats are now far more interested in hake than cod. And he acknowledges what is too seldom acknowledged - that the Spaniards are fishing for a home market hungry with appreciation for fish. Reflecting on criticism of the EU Common Fisheries Policy, he wonders whether governments understand there is a social function to keeping people in fishing ports. Whale-watching is now a form of employment for redundant fishermen in the growing marine leisure industry, but he condemns a world which reduces nature to demonstrations for entertainment and education. This, he says, is "something far less natural than hunting".
The leaven of his concern is six centuries of cod recipes, including "Communist-style salt cod" and "broiled cod sounds". While quoting Leopold Bloom from Joyce, Kurlansky notes that the great Irish breakfast does not include cod roe anymore - and is becoming more like the English fry.
People who know fresh cod agree on three things, he says: it should be cooked quickly and gently; prepared simply; and it must be a thick piece.
Such is the predilection for the simple dish in Norway that there are even cod clubs. Male-only, applicants often have to wait years to get a place. So the fish which has been responsible for so much has even spawned a new type of late-20th-century social activity - cod bonding, bedad.
Cod: A Biography Of The Fish That Changed The World by Mark Kurlansky will be published by Jonathan Cape in hardback on February 5th, price £12.99 in the UK