To understand the mysteries of being human, look no further than Rembrandt

We’re in the presence of great art when we don’t have to use words like commodification

A Woman bathing in a Stream by Rembrandt in 1654 (The National Gallery )

Question: What makes great art? Answer: No idea, but we know it when we see it. We knew it when we saw it at Tate Modern’s Matisse: The Cut-Outs earlier this year and we know it again at the National Gallery’s equally overwhelming Rembrandt: The Late Works. What the two exhibitions have in common, other than genius, is the old age of the artists. Forgive my preference, but age beats youth in most instances when it comes to art, which is why I was never much sold on the Young British Artists phenomenon. Maybe later, I thought. Maybe when they’ve lived a little and find themselves less interesting. You will tell me that the age of the eyes of the beholder has something to do with this. So be it. We that have lived so long know better how to look than those whose eyes have still to open. And better how to think as well. But I’m not looking for a fight. Fighting being the only thing the old don’t do as well as the young. That, and optimism.

There was another obstacle besides youth, self-engrossment and unmerited attention which the YBAs had to overcome: art itself. Art is always partly its own subject, but to the children of Duchamp and Warhol it was nothing else. Here’s one of the ways we know when we’re in the presence of great art: we stand before it like men and women, stripped of curatorial cant, without once needing to use words like commodification, discourse or appropriation. Great art shuts us the fuck up.

Scratching his head over the scene in Anna Karenina where Levin takes an eternity getting to his own wedding, the critic Matthew Arnold traps himself in an unnecessary distinction. “We are not to take Anna Karenin as a work of art: we are to take it as a piece of life... The author has not invented and combined it, he has seen it... what his novel in this way loses in art it gains in reality.”

Arnold’s field was poetry. In his essay on Anna Karenina, he seems to be reading a novel for the first time in his life. We to whom novels are meat and drink know it requires art to hide art. Reality and art are not opposites for us. Nonetheless, the reading experience Arnold describes we recognise. Tolstoy’s masterpiece does seize us in this way; we do lose ourselves in the illusion of its reality; no Duchampian imp of aesthetic self-regard interposes itself between the work and the impression of life.

And as with Tolstoy, so with Rembrandt. You take in Rembrandt as you take in the living, and though you don’t forget you are looking at paintings, you marvel at what the art does not stand in the way of. Rembrandt, like Tolstoy, catches life in the moment of its being experienced, not by exemplars or prodigies, not by heroes or villains – though incidentally they might be either – but by those to whom being alive is absorbing and perplexing, the thing above all else that they do.

I don’t recall anyone smiling in any of the Rembrandts currently on show at the National Gallery, nor anyone weeping. His subjects exist between grief and happiness, not posing for him, but not helpless victims of his scrutiny either. Neither out nor in, they are of overwhelming interest to him to the degree that they remain undiscovered countries even to themselves. We who are beguiled by our personalities and smile dazzlingly into our own camera lenses have evolved beyond the interest of a Rembrandt. We have betrayed the conundrum of our being.

What strikes us in the majority of Rembrandt’s late portraits is the nakedness of our encounter with the subjects; we take them much as we take people in the hour of our meeting them for the first time, before they become a disappointment to us on account of what they believe, who they look up to and what musicals they like. No one is insignificant in the existential space he occupies; it’s only when we get to know him and his opinions better that we wish we hadn’t got to know him at all.

Rembrandt is first and foremost a painter of the human mystery. The only portraits that could be said to fail in this exhibition are those of the Apostles. And they fail because the Apostles come to us pre-ennobled by their Christian beliefs. Otherwise, the subjects of his portraits have nothing to recommend them but themselves; they are ennobled only by the fact of their being human.

The outstanding work in this show is Bathsheba at Her Bath, a painting of such breathtakingly fleshly sumptuousness that one might say the person hasn’t lived who hasn’t seen it, and having seen it has no more living to do. But it is profoundly touching too – Bathsheba naked, lost between wondering and compunction, holding the proposal from King David which, if she acts on it, will make her an adulteress. If you want to see a conscience painted, then here it is. That her exquisiteness is what’s got her into this, and that her conscience is therefore close fellow to her beauty, is the painting’s subject. It is as though to paint the one is to paint the other. Bathsheba’s very skin is infused with introspection.

We are, of course, not a million miles from Anna Karenina herself here. In her, too, there is this conflation of loveliness, expectancy and remorse. Tolstoy set out to write a cautionary tale of sexual wrongdoing when he conceived Anna Karenina, but the novelist in him got the better of the moralist. There seems to be no such warring of impulses in Rembrandt’s painting. He is neither sensualist nor preacher. To be human is to tempt, be tempted, to long for and regret. In the end you could say that Bathsheba at Her Bath shows how burdensome it is to be human, how human it is to be burdened, and why the story of that humanness is the only story to be told.