We in the media tell our audiences about the times we live in. That is our job. But it is difficult to understand the story of our own times if we know little about other ones.

So when off duty, I tend to read about the past. This is sometimes better done through fiction than history. Even the most visionary writer lives in what WH Auden called “the prison of his days” . His work expresses his era, whether he likes it or not. But sometimes lesser writers, being less sensitive to posterity, speak more directly in the voice of their times.

This Christmas, I have finished Masterman Ready, by the 19th-century novelist always styled Captain Marryat. If he is remembered at all today, it is for his The Children of the New Forest, but he was a real-life sea captain roughly 200 years ago.

From the very first sentence of Masterman Ready, the action is on board “a large ship … running before a heavy gale of wind”. The ship is called the Pacific, but the storm which hits it is in the Atlantic, south of the Cape of Good Hope. It is carrying “a valuable cargo of English hardware, cutlery and other manufactures” to New South Wales.

Also on board is a 12-year-old boy, William Seagrave, and a “weather-beaten old seaman”, whose “grisly locks” stream in the wind. This is Masterman Ready, 50 years at sea.

The captain is knocked out in the storm. Believing that the Atlantic will smash the Pacific, the first mate and the crew take to their best boat, with their insensible captain, and abandon William, his parents, his infant brothers and sister, and the family’s black servant, Juno.

Of the crew, only Ready refuses to go. He stays with the Seagraves. Thanks to his skill, the battered ship is steered to a desert island, and there she rests, “firmly fixed, fore and aft, upon a bed of coral rocks”.

Almost the whole ensuing story is set on the island. Under Ready’s expert guidance, the Seagraves recover whatever they can from the wreck, build a house and storeroom, and start to cultivate the land. Later, they save two tattooed Indian women who arrive in a leaky canoe from another island and treat them kindly.

The women escape at night, however. Fearing they will return with their kin to attack the little English party, Ready insists on building a stockade. Eventually, hundreds of “savages” do appear, wearing war-paint and brandishing spears. They attack the stockade, and are twice beaten off by the well-prepared muskets. Then there is a third attack. The consequence, which I shall not fully reveal, is a combination of triumph and tragedy.

The book’s utter plainness is fascinating. Although Marryat’s descriptions are vivid, they are unadorned. Indeed, part of the novel’s intention is practical. It is meant, I think, for boys like William in their early teens. It tells them, via Ready, how to blaze a path through a wood, plant guavas, erect a stockade etc – almost foreshadowing the Scout Movement.

The morality is unadorned, too. “Sailors,” Marryat writes, “are never discouraged by danger as long as they have any chance of relieving themselves by their own exertions.” Such exertions are what make them good men. But the mighty sea itself always warns them against any pride. Ultimately, they must accept the unsearchable ways of Providence.

The very names of Seagrave and Masterman Ready himself remind one that Marryat draws on the tradition of John Bunyan’s The Pilgrim’s Progress. Masterman is the name of Ready’s godfather who both played his family false and yet set up young Ready – who had saved his life – in a fortune which the boy then lost when the French captured his uninsured ship. A Masterman, the book is telling us, is something no man can be. All that a man can – and should – be is ready for whatever life may throw at him. After losing his fortune, Ready humbly resumed life “before the mast”; that is, as an ordinary seaman. When life throws death itself at him, he proves himself Ready not only by name but by nature. He cheerfully accepts death in the service of others.

I don’t think anyone today could write a comparable novel about boyhood, manhood, God, duty and the sea, or would dare to try. Yet today there will be even more boys alive who long for inspiration about how to be both brave and gentle. A huge gap in the market has opened up.

There is yet another point on which Marryat is deeply unfashionable. Although he never uses the word “empire”, the global naval power of Britain lies behind the whole story. Ready is consistently merciful to non-white characters – arguing, for example, that the Indians’ desire for the ship’s iron is no worse than the white man’s lust for gold. But he has no doubt that he is part of a “civilised” nation, whereas the “savages” are not. It is a British schooner which, at the end, comes to the rescue.

Interestingly, although some would now find the language uncomfortable, Marryat puts the most eloquent tribute to Ready into the mouth of Juno, the resourceful black servant whose courage never fails, “Oh Massa! I sit by him just now; I take off the flag [the ship’s ensign draped over Ready’s corpse] and look at his face, so calm, look so happy, so good. I almost tink he smile at me.”