Most painters, whatever style they eventually adopt, generally start their career by setting their own likeness down on canvas. It is a kind of baptism by fire attempted once and usually abandoned. This we know because there are far fewer portraits of artists in middle or old age than in their youth. For while the self is best known to self, capturing its essence in one image so that it transcends physical appearance is a mighty difficult affair. The eyes may be mirrors of the soul, but in realistic portraits there are too many temptations to gild the lily and enhance both them and the other bits.

Rembrandt was unusual in this regard. Through his lifetime he recorded the ravages of time, physical decay and fortune in over 70 self-portraits, starting from his youth in Leiden in the late 1620s to the year of his death at the age of 63 in Amsterdam in 1669.

More than any other painter (barring Picasso, Dali and Warhol), his name summons up a precise image of his physical appearance in people's minds. Besides these genuine self-portraits, there are others by his students, over whose attribution controversy has raged for years -- did Rembrandt paint them himself or were they the work of others?

Thanks to infrared investigations and carbon dating of the canvas and pigment used, some misattributions have now been rectified. The "Self Portrait with Gorget" from Nuremberg is one such example. Hitherto thought to be a copy, it is now considered to be an authentic Rembrandt and is now on show at the National Gallery in London, in an exhibition of 60 of his self-portraits. The exhibit has been jointly organized with the Mauritshuis in The Hague, where the show will travel.

But as the exhibition reveals, in this age of the psychiatrist's couch and the confessional, Rembrandt's relationship with images of himself was not what it has been made by some to seem. He was not a man engaged in a lifelong quest for personal identity via his art, although this certainly was one element among many. He was an artist who made his living through his work and, being financially challenged for the majority of his life (except a brief period in the middle) was always conscious of the need to sell. In practical terms, using himself as a model eliminated the need to pay modeling fees.

In the first work of the exhibition -- a tiny etching on a plate he reused from "The Flight Into Egypt" -- he is peering into a mirror, the better to depict himself for his viewers. We see the scruffy miller's son from Leiden with an unruly shock of curls and the familiar bulbous W.C. Fields nose. There is no romanticism here but rather a concern for authenticity, for as with many of these portraits and indeed his later paintings they were in a sense self-advertisement.

What you saw was what you got. Paintings, the objective of which was to wow one's client with meticulously accurate portrayals of different character types, were called tronie. In order to lure a potential client it was necessary to have a full portfolio that displayed one's virtuosity. For portraits this meant the ability not only to show the human face in all its moods and fancies, but also the body clothed with as rich an array of fabrics of distinct and contrasting textural differences as possible -- lace, velvet, brocade and gold-thread embroidery.

When the painting in question was of a historical subject, it was also customary for an artist to include himself and his patrons, Hitchcock-like, in the final composition. Rembrandt appears in different guises in these works. Even where it was a self-portrait, the clothes told much of the story. We see Rembrandt in an early work play-acting the part of the stereotypical Oriental with a feather in his turban, a velvet cape and a silk robe that glistens.

At other times he seemed anxious to pitch his precise artistic and social ranking through the medium of his clothes. Six years after his marriage to the well-heeled Saskia van Uylenburgh, when his fortunes were at their peak, he portrays himself after the manner of Titian, seated at the window and wearing the costume of a cultured man of means. However, even then the choice of clothes was as much a comment on his own improved social standing as it was a style book for his clients to show them the manner in which he would depict them.

Advertisement or not, they clearly held greater significance for Rembrandt. Their power lies not in his costumes or even the poses he adopted, but in his portrayal of himself. For he was as accurate in his depiction of his face as he was with the textures of the clothes. One can track the rise and eventual fall of his fortunes just by looking at what he is wearing, as in a late portrait of 1652 where he is dressed in the shabby studio clothes on which he would wipe his brushes. However, it is the expression on his face that rivets the viewer, whether the signs of hardship etched on his features in later years or the confident but questioning look of his early career.

In 1656 Rembrandt declared himself bankrupt, reduced by 1662 to selling off Saskia's grave. He had returned to self-portraiture in the mid-1650s, in part because images of the famous -- even the bankrupt famous -- were popular, and Rembrandt's work was as much in demand as before. They were the contemporary equivalent of pop star posters today. But in his last portrait in the year of his death, at 63, we see that he has abandoned the role-playing, and like that first small etching that begins the show, this is the man in the raw.

One critic has perceptively noted that in the early work, Rembrandt looked outward, in this last image he looks inward, perhaps to a personal life strewn with the wreckage of tragedy and difficulties, self-inflicted though many of them were. It is an image of a 17th-century man that also embodies the spirit of this age.