I didn’t fall in love with fishing until I was 30. One September afternoon in Scotland, an old schoolfriend, Nick, rigged up a rod and walked me to a sluice gate near Golspie. Salmon can be kind to learners. On my third cast I hooked one. The tug on the line had the firmness of a handshake, and was a reminder of the hand in my favourite childhood legend, finning up from the riverbed to catch a sword. The passing of Arthur was the first thing I read that caused me to burst into tears.

That five-pound handshake at the sluice gate welcomed me to a world I had previously wandered through with eyes half-closed. I began at last to understand Nick – someone I’d known since I was 12, but had not fathomed until the moment of my own induction. When he plopped his line into the unknown he was trading in mystery, or what psychologists might call a water-based religion. For Nick, I realised, the world was cast afresh each day he fished; each cast a personal prayer.

“There is no going back in the matter of sensation,” wrote another fisherman, Ernest Hemingway. From then on, I piggybacked off my work as a journalist, and fished in Iceland, Patagonia, Tasmania, Canada. I caught my first “trophy” on Lake Snyder near the Arctic Circle. There was a boil on the virgin water as the pike surged after the lure, darkening to a bluish green the instant before it struck. I thought at first this was a “lunch fish”, but in a reverse of the normal angling story the pike grew in the net until, by the time my Dene Indian guide held it up, it had expanded to 47 inches. “Jesus, people go their whole lives without catching a fish like this.” He stroked it back into the water, and gradually the dorsal fins straightened and the pike glided off, shaking its head as if it had been at the dentist. The effect of sharing the company of this creature, if only for a few seconds, was to make the energy drain from my body and my limbs shake. I felt privileged, connected, italicised. I felt like shouting, as the American fisherman and novelist Thomas McGuane shouts after landing an 18 pound trout: “I’m a human!”

Purists will open the bellies of their catch to study what the fish has fed on and so choose a suitable lure. Because I let him go, I never found out what my pike had eaten. Yet it is odd what treasures you do find in a fish. One 17th-century pike was found to have a human baby in its stomach, while on Midsummer Day 1626, a sizeable cod was caught off the Lincolnshire coast and taken to the Cambridge fish market where a slimy canvas sack was located inside it, containing three treatises bound together. “This Booke was then and there beheld by many with admiration.”

Aptly, my fishing mentor Nick was a book publisher. It was with him and another publisher, John Hatt, that I discovered the River Hodder in Lancashire, where I have gone for the past 20 years, usually with the same two companions, to fish for sea trout.

The similarities between anglers and authors have long been trawled over. The angler has to know how to read: the position of the sun, the speed of the water, where the fish live, how the fly will present itself across a stream rippling with maybe ten different currents. He selects a fly from his fly-book, and his method of casting his line – the way it blossoms back, or doesn’t – has this in common with a line of prose: it cannot hide his character – although, paradoxically, everything condenses towards trying to suppress that character. To have any chance of catching a fish so alarmable as the trout, you have to blend in with your surrounds, take on their pace, distil yourself into a still and silent shadow until you are indistinguishable from the trout.

As always on my first morning on the Hodder, I squirm along the bank: this impatient, messy, blind, noisy form a crushing argument in my own person against the qualities needed to catch a fish.

My aim is simple: to untangle myself into becoming what normally I am not. And so achieve that meditative state in which the contemplating mind is carried forward by the flow of the stream – until it is both cleansed and primed to make connections; to strike, to hook.

Every ounce of concentration is on the fly, which acts as a peephole into a separate world.

My fly today is the gift of a veteran Lancashire fisherman, who has no truck with what he calls “fly-fishing nonsense”. “All you need is a piece of pheasant’s tail and some copper wire, preferably plum brown in colour from an old transistor radio, and some ochre strands of wool.” That and a small hook. For him, the perfect hook has a shank length two-and-a-half times the size of the gape, with a round bend. Even so, he cautions, it’s not enough to put a line out and wait. “The secret is concentration. Brain, muscle, ear, eye have to have coordination. You can’t teach that.”

After flogging the same stretch of river for 20 years, I still consider myself a novice, pre-linguistic, overly conscious of the gap between the fish and the word. Yet the large sea trout I am hunting, which I spotted rocketing vertically out of a calm elbow of water, is only a decoy. What I love almost best about fishing is another property it shares with reading and writing: it concentrates the mind, while at the same time liberating it. It is much less about catching a fish than releasing the fisherman.

This ecstatic dreamtime lies within the reach of anyone able to bait a hook and is what many of us, really, are angling for – a settled but excited state of mind in a place of outstanding beauty. The late art critic and passionate fisherman Robert Hughes, referring to the mystical connection that can result from such a combination, calls it a “feeling of oceanic peace and oneness with the universe”. This, as he knows, is close to the language of organised religion.

Hughes is not alone in appreciating why Christianity should have adopted the iconography of his favourite pastime, a fish sketched in the dust a coded emblem of one’s faith.

Does any other sport appeal so shamelessly to the Bible? Anglers like to remind us that Seth, the son of Adam, was a fisherman, as were four of the Apostles who were mending their nets when Jesus offered to make them “fishers of men”. Which recalls my number-one pescatorial story. It is about a Chinese sage who sat all his life by a river, dangling a straightened hook in the water, catching nothing. Word of his peculiar habit spread throughout the empire until it reached the ears of the emperor himself who one day made a detour to the river. “Pardon me,” he asked the sage. “What on earth are you fishing for?” The old man turned to the emperor: “You.”

Finally, on my second afternoon, I feel an ominous tug. If ever there’s a “moment of truth”, this is it. The fish will either escape, leaving me holding a straightened rod (is there anything more dead?), or the fish will not escape.

Not a sea trout, alas. Merely a six-inch grayling. Which tenderly I return.

Yet I am not cast down. For fishermen, even the smallest grayling lifted flashing from the water stands as a true image, a true sentence, the scrap, as it were, of a greater truth. A muscle of light and agitated life that connects the angler to the universe. “In looking for one fish,” says McGuane, “you find another – and maybe in the end you find it all.” You just have to look.

A longer version of this piece can be heard as part of BBC Radio 3’s essay series “Looking Good”, on 31 January at 10.45am