The European art world is preoccupied this summer with the question of whether painting is about to be abandoned forever as we enter the 21st century. There are no paintings at all at the Documenta, a contemporary art show staged every five years in the German city of Kassel, and this year's Venice Biennale features fewer painters than ever before.Before they make up their minds on the future of painting, the critics would be well advised to make a detour to the Martin Gropius Building in Berlin where a massive exhibition illustrates how modern art has arrived where it is today. The Age of Modernism looks at the art of this century through about 400 works by 130 artists.But instead of taking a chronological plod through the century, the exhibition follows four separate paths, each of which traces, from a different point of view, art from the beginning of the century to the present. That means that the visitor goes through the century four times, first from the point of view of Reality and Deformation, then Language and Material, followed by Abstraction and Spirituality and finally Dream and Myth.At the start of each stands a great artistic personality, a key figure who acted as a pioneer and decisively influenced the development of art. Picasso dominates the first, largest section, Reality and Deformation, which looks at the changing ways in which artists sought to portray reality. From the Cubism of Picasso and Georges Braque to the Italian Futurists and the German Expressionists, art was revolutionised at the start of the century by the discovery of colour and form as independent means of expression. The first World War was followed by a temporary return to a secure classical order in many European countries and one of the theses of the exhibition's curators is that modern art came close to extinction during the 1930s.Its condemnation by Hitler as "decadent art" and the persecution of artists was aimed at destroying the intellectual and formal achievements of the modern movement. But the ploy failed and, with the hindsight of historical distance one could even argue that the persecution of modern art ensured its survival because it gave it new stimuli. From now on, modern art became associated with freedom itself.THE invention of photography was expected to make portrait painting redundant in the 20th century. In fact, there are very few major artists this century who never painted a portrait and a large room in the exhibition traces a century of portraiture from Picas- so's early works to a gleaming metal bust by Jeff Koons. The first section of the exhibition includes works by Francis Bacon and the German painter Georg Baselitz, famous for his upside-down figures, but ends as it began with Picasso.If Picasso was the towering figure of realistic art in its broadest sense, in the section called Language and Material it is Marcel Duchamp, whose ideas revolutionised art and are the most profound influence on the art of today. Duchamp shocked the art world in 1915 when he exhibited what he called "ready-mades", objects such as a urinal, a snow shovel or a bicycle wheel and called them works of art.By selecting brand-new and other found objects and calling them artworks, Duchamp introduced new answers to the perennial question "What is Art?". For him, the artistic act lay in the choice of an object, its incorporation into an artistic context and its naming - in short, the concept and the name.Almost all of Duchamp's readymades are on show here and their influence is eloquently illustrated by juxtaposing them with later works, such as Robert Rauschenberg's "combine paintings", Andy Warhol's Pop Art portrayals of everyday objects and Jeff Koons's Hoover Vacuum - a group of vacuum cleaners in a sealed glass case.The third section, Abstraction and Spirituality begins with one of the main attractions of the exhibition, two works by Wassily Kandinsky which mark the beginning of abstract art. Composition VI, on loan from the Hermitage in St. Petersburg and Composition VII from the Tretjakov gallery in Moscow are being seen together in Europe for the first time in more than 80 years. This examination of abstract art includes many Russian treasures from the Constructivists and the Suprematists but, once again, the emphasis is on making connections between the work of artists from different countries and periods.THE final path through the century, Dream and Myth, describes an art in which the unconscious breaks through - collective and individual conscience, memory, fear and vision. It moves from the calm, but strange classical images of Giorgio de Chirico, through the Surrealism of Salvador Dali, the video art of Bill Viola and the photographs of Cindy Sherman in a journey through the 20th century imagination.This magnificent exhibition, which cost the equivalent of £6.1 million to stage, was originally due to travel to London and New York but few lenders could be persuaded to part with their treasures for longer than the show's run in Berlin. It is a rare treat for the German capital and an eloquent testimony to the resilience of Modernism and, indeed, of modern painting.The Age of Modernism - Art in the 20th Century is at Martin Gropius Building in Berlin until July 27th.