First things first. This is a very good book indeed, probably the best overview of the cinema ever written. It sparkles with insight, is packed with anecdote, and pulses with passion for the medium that Thomson has been attending to, worrying at and writing about all his life.

Although it may not be an entirely original insight, Thomson again and again presses his case that the attraction of movies is that they play with and on our dreams and deepest yearnings. People go to the cinema, he writes, to sit in the dark "beholding an orgy of their own desires burning on the screen", yet, paradoxically, the net effect can be a deadening of the spirit. Hence his book is not only a paean to "the pictures", as we used to call them, but also an expression of anxiety "over the general impact of moving imagery and our becoming more removed from or helpless about reality".

Thomson, who was born in London but now lives in San Francisco, is 71, which means he is a son of the black-and-white era. He writes with all the excitement and expectancy of a 12-year-old kid, bottle of Coke in one hand and a bucket of popcorn in the other, on his way into one of those gilded cinema palaces of yore to watch with delight and voluptuous terror Rita Hayworth stripping off her shoulder-length gloves in Gilda.

Though he can discuss story-arc or the auteur theory with the best of them, he never loses sight of the fact that "movie", as he calls it offers us childish entertainment, while at the same time shining a light into the deepest crevices of our desiring souls.

Again and again he returns to the theme of film, all film, as a fantasy of eroticism or violence, or both  "It's a pattern of dread and desire." Writing of Jean Vigo's masterpiece L'Atalante, he observes: "Vigo believed that every life is just a pale skin wrapped around a seething inner life, and he knew that film could uncover it."

A few pages earlier, considering the infamous opening shot in Luis Buñuel's silent surrealist short film Un Chien Andalou, in which a razor appears to slice open a woman's eyeball, he insists that "the pressing implication of the picture is to say, oh, please, don't let's peddle the old lies about good entertainment, movie stars and a great evening out  this is a frenzy, bent on sex and violence, and we are growing older as we watch ... Art is not a recreation, a consolation, a pastime, a business (though it is all these things); it is the stone on which your knife is sharpened."

His book, he says, is about screens: "it's Muybridge to Facebook." He begins at the beginning of "movie" (yes, in time that word does become somewhat irritating), which he considers to be the stop-motion photographs of that troubled Englishman Eadweard Muybridge  himself something of a noir figure. Muybridge was born Edward Muggeridge in Kingston upon Thames in 1830. He moved to America, where he suffered an accident that damaged his brain in some way, and when in 1875 he murdered his wife's lover, he based his defence on a claim of insanity; the jury rejected the claim but acquitted him anyway on the grounds of justifiable homicide. Updated, the story could have made a nice little black-and-white thriller directed by Billy Wilder or Howard Hawks, with maybe a script by Raymond Chandler.

Thomson notes that Muybridge's photo series of animals in motion, or of naked men and women walking or running or performing mundane tasks, have no intrinsic dramatic tension, tell no story. "The pictures were the sensation ... He shot people, but he also shot light, air and passing time ... The pictures feel ravished by the play of light on ordinary physicality and by the tiny, incremental advances through time." They also made people aware of themselves engaged in the act of watching.

Not for nothing does St Paul's version of Christianity brand certain forms of looking as sinful. Part of the pleasure of being at the movies is that in exchange for a few coins we will be allowed to crouch in the dark for a couple of hours and feast our eyes on images of flesh and blood creatures getting up, or down, to all sorts of things we are not at all sure we should be seeing. The cinema makes voyeurs of us all.

Thomson's running theme is the relentless, profound and subversive effect that cinema from the outset has had on us. "I have tried to show," he writes, "how our attitudes to love, identity, desire and responsibility have been shaped by moviegoing. These topics come together in the large subject of acting: of whether we are ourselves or someone playing ourselves. And whether the movies have been good for us."

For his part, he is helplessly in thrall to the cinema, and his book is a lover's discourse, awed, excited, at times positively ecstatic. Yet even he has his moments of doubt. "There was a period  fifty years, if we are generous  in which the light was enlightening and moving and even transforming. But then a change set in where the shining light might become a mockery of enlightenment and a means of imprisoning the masses."

Although he has no illusions about Hollywood and the people who run it, there are no real villains in Thomson's book. He does, however, find cause to shake his head over Steven Spielberg, in his making of Jaws. In that movie, Spielberg produced an affectless vehicle that thrilled and even seduced, and yet was, essentially, about nothing at all. Thomson imagines a reader objecting that King Kong, for instance, was not "about" much either, and replies: "But if you put King Kong and Jaws in the same sentence you have to feel the naive poetic impulse that inspires the earlier film, and the cold-blooded detachment in Jaws."

Thomson worries that something happened to the cinema around the time of Jaws, something cynical, sinister and perhaps even fatal. Part of the fun of Jaws and the other mindless thrills-and-spills imitations that it spawned, he says, "is that the commotion meant nothing. The sensation eclipsed sensibility". This is the contentious heart of The Big Screen. The deadening process that, according to Thomson, set in the 1970s has now spread across the billions of tiny screens that infest the world, the combined sickly glow of which must be visible from outer space. Watching has become mere gaping, open-mouthed and slow-breathing. "Facebook already takes our earnest admissions about ourselves and trades them for advertising."

Thomson could never be accused of pessimism, and his book is a glorious celebration of one of humankind's great inventions: a form of public poetry that the ancient Greeks would have recognised and revelled in. Even if the end is nigh, the evening has been great fun: "We have seen amazing things near death; and if the movies are dying, the long-running funeral has been a show to behold." All the same, when the lights come up, something of the darkness endures.

The array of watching devices that have swept over "cinema" in the last thirty years will accelerate and spread, and of course they are helpful and profitable  just look at the economy they have produced. Might they also be the lineaments of a coming fascism? Don't be alarmed, it will be so much more polite or user-friendly than the clumsy version of the 1930s, but as deadening as the shopping malls of Americana, the nullity of so many of its schools, the unending madness of its advertising, and the stony indifference of technology.

Gulp.

 John Banville's Ancient Light is published by Viking.

David Thomson is a metaphysician of the movies  a unique guide to what happens when, like Plato's cave-dwellers, we cluster in the dark to gaze at a light that is refracted, second-hand, the shadow of dancing bodies and dreamily beautiful faces that once burned an impression of themselves on to film. Plato's cavemen looked into an illusory fire, with the sun behind them; we watch brightness projected on to a screen, whose purpose is to conceal reality not reveal it. Are we huddled there in the hope of enlightenment or do we have a devious need for the darkness, which gives us licence to dream with our eyes open and to fantasise about the mayhem and murder acted out for our enjoyment?

In 1967 Thomson's first book, Movie Man, examined the strangeness of what had become "a visual society" and worried about the ethics of "a visible society", ruled by snooping cameras. After a dozen or more collections of essays, semi-fictional rhapsodies addressed to Warren Beatty and Nicole Kidman, and that opinionated encyclopedia of opinions A Biographical Dictionary of the Cinema, he returns now to the subject that has preoccupied him all along: how did movies alter the collective consciousness?

Movie Man had a McLuhanesque enthusiasm for the electronic future, but fretted, in its account of the book-burning in Truffaut's Fahrenheit 451, about the possible loss of an older wisdom. That revolution has happened, and Thomson today is a septuagenarian movie man who laments the end of cinema. In an affluent society, we're so mobile we don't need movies: car windows are "screens that give us a travelling show". But the young don't look out of those windows; they are fixated on screens the size of their palms, which open on to a Facebook page where, in a parody of what the movies once did, desire is converted "into a fee payment and a surrender to ads". Thomson sees these kids as the offspring of Godard's jittery methodology. Jump-cutting happens inside their heads; their minds are remote control devices, enabling them to fast-forward through life.

Films are a kind of religion for Thomson, and The Big Screen is forever hailing the holy light that irradiates his screens. "The light," he says of California, "is like a gift"; American life, like the movies, promises every citizen a place in the sun. Thomson attributes the fragile lyricism of Ingmar Bergman's early films to the brevity of the Swedish summer, and says that Leni Riefenstahl in her documentation of the Berlin Olympics photographed "mountain light at ground level". Film is flickery, so kinetic that it disappears in motion, like an aeroplane propeller. But the intensity of Thomson's love makes it solidify before our eyes: the black and white nightclubs where Fred and Ginger dance feel, he says, "like hardened cellophane, or film stock".

The light can be malevolent. Think of Raymond Burr's glinting cigarette in the otherwise dark apartment  a den of iniquity like a cinema  in Rear Window. One of the many bravura riffs in Thomson's book concerns cinematic smoking: have movies lost a certain intensity now that actors are not permitted, like Bogey and Bacall lighting up to flirt in The Big Sleep, to suck on fire? Light that once dazzled became lethal when Antonioni, after photographing a news headline about the perils of the atomic age, chose to finish L'eclisse with the sudden ignition of a street lamp on a deserted urban corner.

Thomson has never denied that cinema is voyeurism, and says here that "the sheen in Murnau's Sunrise is the glow of desirability". He stands up for equal-opportunity exposure, and after noting the first appearance of female pubic hair in Antonioni's Blow-Up goes on to blame Brando for playing peekaboo with his penis in Last Tango in Paris: the winter cold of the apartment where the film was made gave the actor's tackle an attack of stage fright. With exemplary candour, Thomson insists that "porn is movies, just like surveillance footage". In a visual society, we have no secrets.

As Thomson's wayward and digressive history nears the present, it strays into alarming terrain. He abhors TV (although he considers the old-time BBC to have been "the best film studio there ever was") because its screens hypnotise us without demanding either concentration or empathy: like electricity, it is a "service" we switch on, and what it provides is not light but "a safeguard against disorder and fear", enabling us to whistle in the dark. It has led to the frenzied fragmentation of YouTube, where you're only asked to look at bits or clips, "the debris from an explosion in the culture". We too have been atomised: film bifurcated reality, turned a person into an image. Everyone, whether or not they live in Essex or the Big Brother house, now stars in their own imaginary movie, or at least their personal sitcom. This, Thomson concludes, is "the alienation that befalls people who live on or through screens".

Judgments like these, when Thomson makes them, have a rare moral force. Elsewhere he contrasts Chaplin's noisy, protesting silence with the stricken quiet of Buster Keaton, or calls the ape in King Kong a tragic lover whereas the shark in Jaws is merely "a vector in the game". Breathtakingly, he says that the New York night in Sweet Smell of Success is photographed to look like "the hide of a crocodile in the moonlight", and he likens the expression of Al Pacino in The Godfather  a "frozen stare as evil consumes him"  to plastic surgery, transfixing his features in a rictus of terror. Cinema may have ended but Thomson's brain is the ultimate repertory theatre, perpetually rerunning our favourites and allowing us to wonder at them all over again. The highest praise I can give him is to say that the images he treasures are just as alive on his pages as they were on the big screen.