Me, myself, I

Why does an artist paint his own portrait? Is it posing, play- acting or self-obsession, or is there perhaps a higher purpose? The 20 or so self-portraits painted by Rembrandt towards the end of his life show a face ravaged by debt, drink and grief. And yet his challenging gaze looks beyond the darkness, bigotry and indifference of his times, with something like hope

In this month of June the old man is looking down from his poster on to the street corners of central London. In fact he was not so old when he painted the self-portrait reproduced on the poster. Probably in his late 50s, maybe 60. Nevertheless, it is a later Rembrandt self-portrait, and these portraits, like the late Beethoven quartets, have gained a very special authority, dark works about error, energy and endurance. Again, like the quartets, they are magnificently unresigned and uncomplaining.

At the age of 63 Rembrandt died, looking, even by the standards of his time, very old. Drink, debts, the death from the Plague of those nearest to him are among the explanations of the ravages done. But the self-portraits hint at something more. He grew old in a climate of bigotry and indifference - not dissimilar to the climate of the period we are now living through. The human could no longer simply be copied (as in the Renaissance), the human was no longer self-evident: it had to be found in the darkness. Rembrandt himself was obstinate, dogmatic, cunning, capable of a kind of brutality. Do not let us turn him into a saint. Yet he was looking for a way out of the darkness. And the appeal behind that searching is there in the self-portraits.

They contain or embody a paradox: they are clearly about old age, yet they address the future. They assume something coming towards them apart from Death.

Twenty years ago, in front of the self-portrait in the Frick Collection (which is in the show opening at the National Gallery on 9 June) I wrote the following lines:

The eyes from the face

two nights look at the day

the universe of his mind

doubled by pity

nothing else can suffice.

Before a mirror

silent as a horseless road

he envisaged us

deaf, dumb

returning overland

to look at him

in the dark.

There is at the same time a cheek, a sort of insolence about these works which makes me think of a verbal self-portrait, in a story I like very much by the American polemicist and fiction writer, Andrea Dworkin, "Listen":

"I have no patience with the untorn, anyone who hasn't weathered rough weather, fallen apart, been ripped to pieces, put herself back together, big stitches, jagged cuts, nothing nice. Then something shines out. But these ones all shined up on the outside, the ass-wigglers, I'll be honest, I don't like them. Not at all."

Big stitches, jagged cuts. That's how the paint is put on.

Yet, finally, if we want to get closer to what makes the late self-portraits so exceptional, we have to relate them to the rest of the genre. How and why do they differ from most other painted self-portraits?

The first known self-portrait dates from the second millennium BC. An Egyptian bas-relief which shows the artist in profile drinking from a jar that his patron's servant is offering him, at a feast where there are many other people. Such self-portraits - for the tradition continued until the early Middle Ages - were like artists' signatures to the crowded scenes being depicted. They were a marginal claim which said: I also was present.

Later, when the subject of Saint Luke painting the Virgin Mary became popular, the painter often painted himself in a more central position. Yet he was there because of his act of painting the Virgin: he was not yet there to look into himself.

One of the first self-portraits to do precisely this is Antonello da Messina's in the National Gallery. This painter, who died in 1479 and was the first southern painter to use oil paint, had an extraordinary Sicilian clarity and compassion - such as one finds later in artists like Verga, Pirandello or Lampedusa. In the self-portrait, he looks at himself as if looking at his own judge. There is not a trace of dissimilation.

In most of the self-portraits which were to follow, play-acting or dissimilation was endemic. And there is a phenomenological reason for this. A painter can draw his left-hand as if it belonged to somebody else. Using two mirrors he can draw his own profile as if observing a stranger. But when he looks straight into a mirror, he is caught in a double-bind: his reaction to the face he is seeing changes that face. Or, to put it another way, that face can offer itself something it likes or loves. The face arranges itself. Caravaggio's painting of Narcissus is a perfect demonstration.

It is the same for all of us. We play-act when we look in the bathroom mirror, we instantly make an adjustment to our expression and our face. Quite apart from the reversal of the left and right, nobody else ever sees us as we see ourselves above the wash-basin. And this dissimilation is spontaneous and uncalculated. It's as old as the invention of the mirror.

Throughout the history of self-portraits a similar "look" occurs again and again. If the face is not hidden in a group, one can recognise a self- portrait a mile off, because of its particular kind of theatricality. We watch Durer playing Christ, Gauguin playing the outcast. Delacroix the dandy; young Rembrandt the successful Amsterdam trader. We can be moved as by overhearing a confession, or amused as by a boast.

Yet before most self-portraits, because of the exclusive complicity existing between the eye observing and the returned gaze, we have a sense of something opaque, a sense of watching the drama of a double-bind that excludes us.

True, there are exceptions: self-portraits that do look at us: a Chardin; a Tintoretto (in the Victoria & Albert museum;) a copy of a Frans Hals self-portrait when he was bankrupt; Turner as a young man; the elderly Goya as an exile in Bordeaux. Nevertheless, they are few and far between. And so how is it that during the last 10 years of his life Rembrandt painted nearly 20 portraits that address us directly?

When you're trying to make a portrait of somebody else, you look very hard at them, searching to find what is there, trying to trace what has happened to the face. The result (sometimes) may be a kind of likeness, but usually it is a dead one, because the presence of the sitter and the tight focus of observation have inhibited your response. The sitter leaves. And it can then happen that you begin again, referring not any more to a face in front of you, but to the recollected face which is now inside you. You no longer peer; you shut your eyes. You begin to make a portrait of what the sitter has been left behind in your head. And now there is a chance that it will be alive.

Is it possible that Rembrandt did something similar with himself? I believe he used a mirror only at the beginning of each canvas. Then he put a cloth over it, and worked and reworked the canvas until the painting began to correspond to an image of himself which had been left behind after a lifetime. This image was not generalised, it was very specific. Each time he made a portrait he chose what to wear. Each time, he was highly aware of how his face, his stance, his appearance, had changed. He studied the damage unflinchingly.

Yet, at a certain moment, he covered the mirror so that he no longer had to adjust his gaze to his gaze, and then he continued to paint only from what had been left behind inside him. Freed from the double-bind, he was sustained by a vague hope, an intuition, that later it would be others who would look at him with a compassion that he could not allow himself.