The collected works of Jacobs Kloppenburg

Ever since Vincent vanished, the Dutch have entertained a mordant fear of letting another artistic genius slip by unrecognised. So, for many decades they have supported the most lavish - if not lax - subsidies for artists anywhere in Europe. Yet it seems the Dutch have once again let a compatriot of outstanding talent go neglected in the heart of Amsterdam, only to receive fulsome support abroad.

It must be admitted that the case of Jacobs Kloppenburg might test the mettle of even the most understanding patron.

Kloppenburg, born in 1930 started working in earnest as an artist at the age of eighteen, and since then has literally not stopped, producing drawings, paintings, photographs, assemblages and everything in between at an awesome daily rate, an oeuvre incalculable in its sheer profusion. In Kloppenburg's case the issue is further complicated by his steadfast refusal to exhibit his works and their unclassifiable oddness.

In practical terms the battle comes down to real estate, namely the beautiful 400-year-old coffee and sugar warehouse on a canal that Kloppenburg has long used as his studio, storage space and general archive (a term granting no indication of the folly and grandeur of his gathered possessions, their mind-boggling chaos).

Without doubt the Kloppenburg warehouse is one of the clandestine masterpieces of 20th century creative individualism, comparable to Schwitters' Merzbau, Facteur Cheval's domain or the Fondation Corbusier, a place where so much stuff has gathered that one can no longer imagine any human able to inhabit its corners. Five massive floors are filled to their ceilings and edges with dense piles of what seems merely like accumulated rubbish, a narrow and perilous path snaking through these junk mountains like alpine crevasses.

Yet Kloppenburg himself knows exactly where the smallest item is to be located.He alone carried everything up the ladder and through a trapdoor into this enchanted domain, and when he pulls something out of the perilous pile one realises all this junk is in fact a work of art: a sheep's jaw holding a plastic globe, a toy pistol sprouting tinsel, an empty milk carton filled with ball bearings, the range of transformed detritus is without limits.

The problem is that viewed as a whole it looks like the largest mess ever made, a mess of messianic, superhuman proportions without end or beginning, the Ur-mess itself. It is understandable how the landlord could view this as insane squalor rather than a unique never ending work-in- progress, especially when that landlord has the opportunity to turn this ancient building into a series of profitable flats.

Kloppenburg, a magisterial figure with flowing white beard and gleaming pate hardly ever speaks and has neither the resources nor inclination to do battle. However his next door neighbour, a combative younger artist with the improbable name of Waldo Bien realised that part of Holland's cultural heritage was under threat. Taking it upon himself to fight the landlord, call in the city council and alert museums and artistic authorities, Bien began a long campaign.

Nobody in Holland was prepared to take the Kloppenburg estate seriously, partly due to its daunting scale, but through his contacts in Germany, Bien - who studied with Josef Beuys - gained the attention of the Van der Grinten family, early collectors of Beuys who were building their own museum to the artist for the city of Dusseldorf. Bien sent a sample 400 Kloppenburg works to Germany, and in an unprecedented coup persuaded them to accept the whole archive. There will now be a Kloppenburg museum in Dusseldorf, possibly built to the artist's own bizarre design and the retroactive shame of Holland's cultural elite has already begun.

Despite the apparent craziness of his stockpiled garbage, Kloppenburg is far from an "outsider" artist and has a variety of supporters in the art establishment, such as legendary curator Walter Hopps, currently running the Menil Collection. Kloppenburg certainly maintains a mythic dimension, archetype of the reclusive artist-genius. Kloppenburg travels the whole time, living rough in Africa where the locals considered him a magician when they saw his young man's body, helped by his taking ice cold showers every morning (along with his collection of plants). Kloppenburg collects property as well as objects, which probably did not help his case with the landlord. He not only has another house in Dusseldorf but also a wife, who endeavours to keep the place relatively empty.

In fact there are only a hundred or so works missing from the collection, due to an error of judgment when he was forced into having an exhibition at the prestigious Fodor Museum in 1986, taking over the museum with hundreds of charming, folkloric pastels which immediately sold out. Kloppenburg stopped his pastels as soon as he realised the danger of popularity and indeed hid on his kitchen floor when collectors came round banging on his door wanting to buy more.

Likewise he cancelled his appointment Rudi Fuchs, director of the Stediljik Museum, not wanting to be known as the "pastel artist" or indeed known at all. Instead of which Kloppenburg preferred to pedal the streets of Amsterdam on his converted bicycle with only half a steering wheel to go through narrow passages, stopping to gather a few more bits and pieces from the gutter, bringing them home to his laboratory. Here he would stay up all night in his hammock with three different radios playing simultaneously, constantly doodling mathematical calculations and sketches as if in a trance. Of these notebooks alone - filled with mysterious signs, alchemical formulas and sketchy hares - there are thousands, each drawing dated with the precise time of start and finish and which floor of the warehouse he was on. The collection is endless, stretching on like a meta-museum out of Borges. Everything has been kept, from his first childhood sketchbooks. Kloppenburg began working at his father's publicity company, doing drawings and lettering, then created a successful range of printed silks with his mother and even thought of becoming fashion designer. But it was as a Constructivist artist that Kloppenburg was best known in Holland, making two works a year to deliver to the government to receive their generous grant.

It is Bien who has taken on the unenviable task of cataloguing and numbering all these works, from painted car doors, stacks of abstract paintings, collages and series of photographs, not least of the artist's dead mother, who he kept at home to study the process of decay perhaps longer than normal. Kloppenburg is constantly educating himself, wanting to learn everything about form, entropy, growth. A faintly perverse element is merely part of this boundless curiosity. When water came in from the roof he started sprinkling watercress seeds everywhere to see how they grew, then floating lights in the water whilst taking notes for John Cage on the sound of the various drips. What looks like mayhem is part of his programme to study the most minute changes, whether the rotting grapes kept on the table or fruit peel artworks, zoological, palentological forms which he scatters in the corners of the room. Of course nothing can be thrown away, but his interest is in development, not preserving old work; he draws on the walls carefully but lets the rain wash them away.

Faced with all this, Bien had a difficult time persuading the local judge that everything needed to be preserved as it was. He described the archive as like a glacier, crossing a border to another millennium, of incalculable value to future visitors. Whilst the legal battle raged and the Dutch media debated the genius-or-madman issue, Kloppenburg kept landlords at bay with a lifelike puppet in his bed, its position changed three times daily by his loyal secretary-doorman, a retired classics teacher.

In the end the landlords could wait no longer, and despite last minute protests the entire warehouse - however many thousands if not millions of works - was cleared away into fourteen gigantic haulage containers currently awaiting shipment to Germany, a new home in their own museum.

Kloppenburg remains philosophical. He is just exercising: "the real work I still have to make".