We then return home with renewed vigour and resolve to do exactly the same, only differently. (Artists have always fed off one another: Picasso was banned from many a studio in Paris because of his ability to suck up an artist's work like a vacuum cleaner, junk what he didn't need and regurgitate the rest in his own work.)
Anyway, there were Barry and I outside a small museum. I forget the name, but they were showing etchings by Rembrandt, two to be precise, in many states - a state being a stage in the development of the image on the metal plate. The etchings were The Three Crosses, a crucifixion scene, and Ecce Homo: Christ Presented to the People.
Seen side by side, as I saw them, the changes that Rembrandt made through each state were a revelation. He was not merely adding more lines and figures to the scenes. He obliterated square inches of beautifully drawn humanity any artist would die for. He maniacally scraped away the metal until figures disappeared and then reworked the plate with new figures or no figures at all.
The superhuman effort in terms of manual work alone was staggering. But what was still more striking to me was that it was as though Rembrandt was cutting through layers of plate because somewhere inside the metal itself lived the trapped souls of those he was trying to free. He was gorgeously mad.
I think it is this purposeful nature of Rembrandt's work in all its forms which pulls me to it. A driving will to exist dominates his whole output, and the unhinged mindset of someone who knows that the rest of the world can go to hell, because he had been there and done that. We both left the exhibition with the uneasy feeling that probably neither of us would ever touch that kind of pinnacle. But what are heroes for if not to prod you over the top?
Rembrandt painted himself throughout his life. He became his own best subject. As long as he painted, he was always there for himself. Portraiture has a very special quality. Time spent with a sitter becomes an important element in the progress of the artist's perception: attitudes are forever changing according to the nature of the confrontation.
What the artist first sees may well disappear as a new persona emerges from behind an initial mask of unfamiliarity. Photographic realism, and a 'likeness', are not the essence of true portraiture unless a fleeting revelation is snatched from the contours of a face in transition. The paint itself is also an object in its own right. It is subject to its own motivation, rules and dynamic which an artist can overcome, ignore or amplify according to ability and mood.
When I confront a portrait by Rembrandt, I am first conscious of the paint, the actual brushstrokes, and only then into focus come the revelations - Rembrandt's raw ability to transform pigment from brush to canvas into living flesh, nuance, movement and a miraculous presence. If mere likeness were the criterion of a good portrait then Rembrandt would now be forgotten.
When he painted a picture which we know as The Night Watch, commissioned by the officers of the City Guard, only six of the 16 figures of 'rank and position' claimed, reluctantly, that their heads resembled them, and yet he was being paid 100/200 guilders per head. 'Then pay me for six,' he replied. 'I was painting men, soldiers, a company marching out with pride. I was not painting vain pedants of rank and position, full of themselves, empty and stupid beneath their big hats.'
At the height of his material success, Saskia, his beloved wife and muse, died, and his attitude to mankind became at best a truculent toleration. In Alexander Korda's biopic, Rembrandt was played by Charles Laughton, who portrayed him as a messianic sage.
'Every man has a destined path,' he says in the film. 'It leads him into the wilderness but he must follow it with head high and a smile on his lips. What is success?' he murmurs. 'A soldier can measure his success in victories, a merchant in money. But my world is insubstantial. I live in a beautiful, blinding, swirling mist. The world can offer me nothing. What I need is a woman I can call my wife.'
Nothing quite filled the vacuum left by Saskia. They had three stillborn children and Titus, Rembrandt's only surviving son. Despite her wealth and his earning power, Rembrandt remained feckless in money matters. The state claimed everything he painted, like a pimp with a chronic cocaine habit.
It was a chambermaid, Hendrickje Stoffels, who occasioned the cataclysmic downturn in Rembrandt's life. They fell in love and Geertghe Dircx, Rembrandt's jealous housekeeper and bedwarmer, sued for a broken troth, accusing Hendrickje Stoffels of 'practising whoredom with the painter Rembrandt'. He continued to spend heavily and gradually the net closed in to strip him of everything he possessed, including all future work he would ever do.
You must look hard at a Rembrandt portrait. Look hard at the eyes. They will look back at you and defy your attempts to understand his secrets. You think you understand but the eyes appear to move and the thoughts behind them have moved on. His etched self-portraits contributed to his growing reputation, perhaps the first examples of self-publicity.
His burgeoning fame from the age of 20 did not go unnoticed by Rembrandt. To personify himself in a self- portrait was to capture that fame, distribute it abroad and transform it into an icon.
For me, the greatest of his etchings is The Three Crosses, which demonstrates that nothing need be finished. Rembrandt pushes the plate to destruction in his attempt to resolve the reactions of the figures at the base of Christ's cross. Each version was sought by collectors as though it were a passing thought to be treasured. And those people were right. The 'unfinished' state remains one of Rembrandt's virtues. The work is finished 'when the master has achieved his intention in it,' according to one of his students.
His 'genre paintings', incorporating a self-portrait in a historical context, also ensured a keen market. Two for the price of one: the artist and his work in one picture. This was commercial art of the highest order.
The Blinding of Samson is a crucial example of satirical potency where Rembrandt is holding the spear and doing the blinding. An artistic sick joke maybe, but so exquisitely orchestrated. All personalised work has been commercial, as long as there have been patrons.
Only cave painters painted for pure and deeply significant reasons. They personified their subject because they were about to go out and kill it to eat. Put a line around that which you fear and you exorcise its power over you. The subject becomes your victim. You are in control. Sign it and you become a god.
Nobody signed their work before the fifteenth century and when they did, it transformed a craft into an art. You make a statement - 'This is a unique creation' - and you satisfy a latent hunger for something people didn't know they needed.
Rembrandt was greatly influenced by Renaissance artists, particularly Leonardo da Vinci. When Leonardo painted The Last Supper, he had several ideas in mind. The first was the portrayal of 12 disciples, real men, ordinary folk, beggars found in the streets of Milan around the monastery of Santa Maria delle Grazie. Their expressions of shock and disbelief reveal not only the mannerisms of each individual but their imagined relationship to Christ.
Leonardo captured a moment, emotionally charged, the first snapshot. Real people expressing natural feelings. The painting was on the end wall of the monastery's refectory, and in fact an extension of its architecture. Its presence blessed the monks with the impression that they were actually eating supper with their Lord. His followers had come up from the streets as they must have done in biblical times. It's as radical an idea as any I can think of.
His use of beggars, who he would have pose for him dressed as a king or a prince, gave Rembrandt an untouchable power over the reality of his impoverishment. It also expressed a disdain for his clients, the wealthy who used artists to present an elevated image of themselves and overcome their own private sense of crippling insecurity. He knew this as well as he knew himself. He would dress in the finest clothes and look out to defy a world as bankrupt as he was.
When he could no longer afford to hire a beggar, he resolutely became his own model and ultimately his finest subject. Not only did he know exclusively how he felt inside, he could express it intimately. The predicament would have suited his rebellious nature and poignantly held at bay the growing fears of his own mortality. By this time, Hendrickje, too, was dead, as was his son Titus, aged 27. Rembrandt was alone and all youthful games were over.
But the range of his abilities never appeared to desert him and the later self-portraits (of 1658 and 1661 particularly) are as brutal a record of life in decline as any have inflicted upon themselves in the name of art. The subject was in complete control of his own constant bombardment. Metamorphosis from middle-aged defiance to tragic victim of life was never more persistent or merciless. The ageing process is stripped of any sentiment, allowing Rembrandt to do what no other painter has achieved. The likeness is immaterial; the ruthless, living paint and its testament are paramount.
And finally, it is not the wearing of kingly attire which lends dignity and grace to his presence but the magnificent sacrifice of himself to the acute scrutiny of his own gaze, and ultimately to ours. Ironically, and blissfully, the later self-portraits are masterpieces of observed, wretched, humanity frozen in time. Rembrandt defeated nature's gargantuan disregard for circumstance and putrefaction and leaves us a legacy of monumental immortality.
While I was writing this appreciation, I was overcome by a desire to do my own self-portrait. It is only a kind of likeness. I was discouraged from attempting a 'Rembrandt' by my art teacher, Leslie Richardson. 'Just do yourself, by yourself. Don't try Rembrandt,' he said, 'or I shall be very disappointed.' I hope I understood what he meant and as I painted, his words kept reminding me of my quest and my dilemma.
I worked through video film, TV monitors, a Leica camera, some weird morphing gismo on a computer and any other device that would help me to avoid a 'Rembrandt'. I recorded the portrait's development on a digital camera, constantly dissolving through from one version to the next.
The result is a frightening evolution, through complete loss of control to a final sense that only I could possibly know that it is finished because I have 'achieved my intention in it'. It will become my portrait of Dorian Gray. The portrait's features will remain doggedly innocent and blameless on life's precarious journey towards a triumphant future. I will look forever young.
Rembrandt By Himself is at the National Gallery, 9 June-5 September. Ralph Steadman's short film about seventeenth-century Holland will be shown on BBC2 on Wednesday.
