You can’t take your eyes off them

    First, it’s an evocation of royalty: splendid, showy, stiff and ornate. A queen is a queen, whatever her age and demeanour. Second, it’s a portrait of a royal brat, a spoilt teenager, barely 17 years old, imprisoned in a vast acreage of black velvet that belongs on someone older and bigger. Third, it’s an accusation of inbreeding. Mariana was her husband’s niece, and the other interchangeable infantas on the walls around her look just like her, because the same dangerous ratios of unmixed Hapsburg blood went into all their makings. Fourth, it’s a painting that plays mind games with you, a mental stand-off between a queen and her lesser: you stare up at her and she stares down at you. Fifth, it’s a piece of preternatural surrealism, because the mini-queen’s absurdly wide crinoline and angry little rouged face trigger sensations of such uncalmable strangeness.

    So that’s what Velazquez brought to art: a superman’s ability to force five tons of ambition into two stone of painting. Whatever the job requires, he invariably gives you more. There’s even a sixth picture in the Mariana portrait. Look at the way her fabulous dress is captured, with those exciting flurries of quick brush strokes that only make sense from a distance. Kenneth Clark used to call what Velazquez did a “fricassee” of paintwork. It’s the prototype of the method the impressionists were supposed to have pioneered 300 years later.

    So large and so obvious is this talent that the National Gallery needed only to gather as many Velazquezes as they could to come up with an outstanding exhibition. They’ve certainly done that here. Four rooms’ worth of his output from every phase of his career has no choice but to add up to a memorable event. The really greedy among us might have lusted after a few more of his noble dwarfs; and the impossible dream of seeing his huge masterpiece, Las Meninas, in England is worth hanging onto, as all dreams are. But back in the real world, the National deserves extra credit for the helpful way it has distributed the goodies it’s gathered.

    For the first time, a large section of the permanent collection has been shifted elsewhere and replaced on the main floor by this temporary display. What a relief it is not to be scraping your head on the ceiling of the Sainsbury basement as you usually must when shows of this magnitude arrive here. Velazquez needs grand spaces into which he can expand, and he’s got them.

    We start with his astonishing beginnings in Seville, where he was born in 1599. When a painter becomes as fluent as Velazquez became, there must always be precocity at the start of the journey, and the evidence for that here is flabbergasting. No 18-year-old has a right to achieve what Velazquez achieved in his first remarkable interiors of kitchens and drinking dives. They’re called bodegones, from bodega, that excellently evocate Spanish word for a tavern.

    And one of the things that’s remarkable about Velazquez’s early bodegones is their unsquashable and unjuvenile seriousness. An old woman fries two eggs in a pan of olive oil. An old man sells water in the street to a young man. A kitchen maid grinds up garlic for a fish dish, while the fish, arranged on a plate in front of her, sport what I swear are expressions of wide-eyed terror on their shiny little faces at the prospect of their ultimate fate. That’s right: the fish can see into their own futures.

    The immense and scarily premature weightiness of these kitchen scenes lifts them immediately out of the realms of still-life and genre painting and into the altogether more exalted sphere of religious art. In a Velazquez kitchen, it is never merely a dinner that is being prepared. Human destiny is also being weighed, sieved and tasted. Every table is an altar. Every death a sacrifice. Every humble kitchen interior a biblical stage on which are being enacted the mysteries, responsibilities and rhythms of a Christian existence.

    Yet this powerful religious art hardly ever mentions religion by name. A couple of the bodegones do actually feature scenes from the life of Christ painted quickly in miniature at the back of the kitchen, to make explicit what is usually implicit. But most do not. I remind you, it’s an 18-year-old who is doing this: who is comparing old people with young people with so much subtle understanding of the paradoxes of life. And look how utterly tangible he makes his fish, his eggs, his jugs and plates, the onions, the garlic, the mortar and pestle of brass, or the trickle of water that has dampened the side of the earthenware jug from which the creaking old Water-Seller of Seville has poured a fresh glass for the young man in the expensive clothes. This is illusionism so potent that it strays into the realms of magic. And underlying it is this fierce Sevillian insight that if Christ was a simple carpenter’s son, then simple things have religion in them. Surely no teenager in the history of art was ever as profound as this, as early as this.

    Also in the opening room are young Velazquez’s first out-and-out religious paintings. I’ve always been guiltily fond of the gorgeous Virgin Mary in the National Gallery’s exceptionally lovely Immaculate Conception. To be honest, I have, in the past, imagined her falling for me, and vice versa. That’s how real she is. Other Spanish painters faced with a commission to paint a full-length Madonna hovering on a magic moon have invariably given us a bland and unblemished Mary of indeterminate age hired from central casting. Balancing on a moon in the sky is, after all, a ludicrous and highly artificial religious situation. But Velazquez cures the artifice with a wondrous shot of realism. His Mary is a delightful Spanish teenager with chipmunk cheeks, her face so closely observed that you can make out the darkening of a fledgling moustache on her upper lip. She might be hovering on a moon above a landscape packed with impossible symbols of her immaculate state, but this utterly tangible young Mary disregards the 400-year gap between you and her, and persuades you of her beauty. This is genius.

    Absurd as it sounds, a part of me wishes Velazquez had never left Seville, never moved to Madrid, never painted Philip IV, never allowed the Hapsburg monarchs to monopolise his talent, and never concentrated on portraiture as he had to. The Seville room is a magnificent crossroads with so many possible directions leading off it. But to Madrid he did go, aged 24, and the royal painter par excellence he did become. Not just of Philip IV, with his camel face and his unshakable royal glumness, but of the royal children, too, the royal dwarfs and buffoons, the royal horses and, in a particularly vivid outburst, of the royal dogs. Put anything in front of Velazquez and he will always paint it as if the truth were more precious than emeralds.

    The Rokeby Venus is here, naturally, her tasty expanse of naked back appealing as always to the masculine tongue. She’s terribly aware of the effect she is having on you, which is why her expression in the mirror held up by the sweet little cupid on her bed is so damned knowing. She sees what you’re thinking. Innocent X is here as well, the pope whom Francis Bacon would later turn so notoriously into a screaming papal monster howling at the gods like a rabid wolf. Velazquez has spotted something unsettling in Innocent as well. Not the dementia Bacon later imagined, but a certainty, a fierceness of conviction, something worryingly close to cruelty, that could and did inspire some jitters in sensitive souls such as Bacon, or me.

    I’m going to stop there. I’m gushing. It’s all useless wordage. Go to the show. You’ll see what I mean.