Until relatively recently German art of the past two centuries had a rough ride outside Germany, and sometimes inside it; even today, whole areas of it remain little known. The Expressionists have come into their own and indeed are rather over-exposed, the Bauhaus was never unfashionable, great isolated individuals such as Klee and Beckmann are recognised as 20th-century classics. The 19th century, however, is quite another matter, for a complex of reasons including politico-historical ones.
The major exception to this unpopularity, of course, is Caspar David Friedrich, the Romantic landscapist whose stock has risen rapidly in the past 30 years. But German painters of the mid-century figure only in textbooks in English-speaking countries, never on gallery walls - whether public or private. German Realism and German Impressionism mean little to anyone except art-history students.
A few years ago, the Tate Gallery in London mounted an exhibition of Lovis Corinth, probably the dominant figure in Berlin art at the turn of the century. It was a superb event, yet attendance was thin and reviews were much at odds with their subject.
The National Gallery in Trafalgar Square has made a constructive effort to close the gap with its exhibition called, rather dubiously, Spirit of an Age. It closed last week. In fact, it covered several ages, from the early Romantics such as Friedrich, Blechen and Carus to the early 20th century.
In between these periods, of course, came the Bismarck age and German unity, which opened a new era in Europe. The paintings all come from the Nationalgalerie in Berlin and those who know the collection there will be familiar with many or most of them. However, it is still rewarding to encounter old friends and discover new territory as well. To draw art-historical parallels with French art - very influential in Germany for at least three generations - works by Monet, Cezanne, Manet etc. have been added.
Friedrich needs no introduction; his pictures with their bleak northern light, frozen figures and slightly melancholic poetry seem to exercise an almost hypnotic effect on contemporary viewers. By contrast, the so-called Nazarenes, who worked in Rome and were forerunners of the Pre-Raphaelites, are very much an acquired taste - dry in colour, nostalgic for the art of the past, an odd mixture of piety and historical pastiche.
Almost the only original genius among them was Carl Philipp Fohr, whose career was snuffed out at 22 when he drowned while swimming in the Tiber. Moritz von Schwind, who in his early years was a friend of Schubert, created a style which mixes neo-medieval romance with a ballad-style folkiness, and which remains remarkably fresh and full of Biedermeier charm.
With the Berlin-based Realist Adolph Menzel, we jump into another and wholly different world, though Menzel was as strong and self-confident in historical subjects as in contemporary ones. His picture of Frederick the Great playing the flute at Potsdam has been reproduced in hundreds of history books, and it remains a tour-de-force in the rendering of artificial light (later in life, Menzel remarked drily "I only painted it for the sake of the chandelier"). The Theatre de Gymnase, painted by Menzel in Paris in 1856, looks forward to Degas, whom it almost certainly influenced, while the monumentally massive picture of a Silesian iron mill challenges Courbet - or any other great Realist artist - on his own ground. It makes a strange contrast to the works of the so-called German Romans, men who emulated the Nazarenes by living and painting in Italy for most of their creative lives.
They too are an acquired taste, but it is richly rewarding to acquire it, since they form collectively a strange, individual, almost magical chapter in European art. The Swiss Arnold Bocklin is the best known and is a predecessor of Surrealism, though his best works are in Munich and are absent from this exhibition. Hans von Marees, an introspective, overcultured Prussian aristocrat, hardly sold a picture in his lifetime and then became a cult figure in the early 20th century; his remote, moody style is close to Symbolism. The third of the Deutschromer, Anselm Feuerbach, was an elegant neoclassicist with a subtle, muted colour sense peculiarly his own.
Contemporaneous with these was the school of outdoor Realism centred on Munich and the personality of Wilhelm Leibl (1844-1900), one of the few non-French Realists who can stand comparison with the very greatest French art of the time. His followers Hans Thoma, Wilhelm Trubner and the Austrian Carl Schuch, are all major artists in their own right and no mere epigones of their master.
WHY they are all so little known, or more accurately so underrated, is one of the puzzles of art history. By this time Germans were coming to terms with "advanced" French art, notably Courbet and, a little later, Manet and the Impressionists. Paris was now the place for young artists to visit and learn from - earlier, it had been Rome and Venice.
However, so-called German Impressionism as represented by Corinth (a European giant), Max Liebermann (attacked by the Nazis in his old age) and Max Slevogt is sui generis and quite distinct from its French counterpart. It has great vigour and a vivid vein of poetry, but in essence it is late pleinair realism, plus a special painterly panache tending to coarseness. The introduction of two early (and bad!) Beckmann pictures in this context does nothing for the show overall, except perhaps to throw it slightly out of kilter. A great artist's growing pains are quite often painful to watch, and Beckmann needed the tragedy of the Great War to bring his gifts into focus.
Not an enormous exhibition in terms of numbers, but, with certain exceptions, one of consistent quality. There are a few gaps, such as the much-loved Munich painter Spitzweg - represented only by a single, immature work. The great Austrian, Waldmuller, is not shown at his best, nor is the remarkable portraitist Ferdinand Rayski, an army officer who took up the brush as a career. However, these are quibbles and after a winter and spring remarkably low in major art events, this one comes like an illumination.