Even for a pro like Cotter, the art of the reclusive but well-connected Ostender eludes categorisation and ready understanding.

Americans who think they know Ensor (1860-1949) tend to regard him as an idiosyncratic loner and scurrilous painter of masks, who railed against the world from the confines of his attic studio stocked with bizarre props from his mother's curiosity shop. This reductive but widely held impression is precisely what persuaded MoMA Curator Anna Swinbourne that the time was ripe for a major Ensor show in the US, where the last one was seen over 30 years ago.

Two additional factors proved convincing: next year's 150th anniversary of the artist's birth and the groundswell of interest among contemporary artists in the Belgian master's work.

The exhibition, which runs until 21 September, comprises 127 paintings, drawings and prints, most of which were created between 1880 and 1900, the period generally considered to be Ensor's richest and most innovative. All of the mediums, genres and motifs which the artist worked in and developed during those early, restlessly experimental years are amply presented. Views of Ostend feature in landscapes, seascapes, townscapes and interiors, while aspects of Brussels (its streets and prominent citizens) can be recognised in social and religious allegories and political satires. Death runs like a current through self-portraits and images of skulls, skeletons, masks and grotesque, tragi-farcical scenes.

Not surprisingly, Belgian collections - principally the country's major museums - are well represented in a show whose major sponsors include New York's Flanders House, the Belgian Ministry of Foreign Affairs and the Society of Friends of Belgium in America. Among the 55 Belgian loans are two important works that have never before been seen in the US.

The outsize drawings -one is over two metres high - are Biblical allegories from Ghent's Museum of Fine Arts, whose director, Robert Hoozee, is the author of one of the essays in the MoMA catalogue. (Michel Draguet, head of Brussels' Museum of Fine Arts, has contributed another.)

These visionary works, whose symbolic subject is celestial light, were included in the Ensor show staged by Brussels' Royal Museum of Fine Arts in 1999. Although roughly twice the size of MoMA's current exhibition, the Brussels presentation focused on the same two decades of the artist's nearly 70-year career.

Ensor continued creating until a few years before his death, by which time his faith in his own genius had been vindicated and his vituperative spirit appeased. Scorned early on by academics and modernists alike, his art was, in the end, collected and celebrated in his own country. So sensitive that he had frequently portrayed himself as the persecuted Christ, Ensor was made a baron and honoured with an enormous retrospective at Brussels' Centre for Fine Arts Museum in 1929.

But by then, the quality of his production had been slackening for almost 30 years. Compared to the experimental, wildly heterogeneous and caustically defiant work which preceded it, much of Ensor's 20th-century output seems tame - sweet and effervescent, rather than dark and biting.

By focusing on the early work, MoMA presents the radical non-conformist who, milking a persecution complex and in retreat from the art world, created pictures which were unlike anything to be seen until the 20th century. Harbingers of the Futurism, Expressionism, Surrealism and Abstract Expressionism, Ensor's trend-flouting images still appear wonderfully strange, inventive and disturbing.

After its run at MoMA, the exhibition James Ensor travels to the Musée d'Orsay in Paris, where it will be on view from October to February, 2010

www.moma.com

Happy Birthday, James
To mark the 150th anniversary of Ensor's birth next year, Bozar will stage an exhibition at the ING Cultural Space in Brussels. The show will be drawn from Antwerp's Museum of Fine Arts, which has the world's largest Ensor collection and will be closed for renovations. Also next year, Ghent's Museum of Fine Arts and SMAK will co-organise an exhibition of contemporary works by artists who admire Ensor today.