El Greco and Modernism, Kunstpalast, Düsseldorf Urs Fischer: Madame Fisscher, Palazzo Grassi, Venice

Careful curators let us see how a rebel Byzantine painter cast a spell over Picasso et al

At the start of the Düsseldorf Kunstpalast's magisterial show, El Greco and Modernism, is a small panel, egg tempera on wood, of St Luke Painting an Icon of the Virgin and Child. Its battered state apart, there is something wrong with the picture. St Luke is making a proper, Byzantine icon, painted without perspective; but the image in which he does so is painted perspectivally. The work is a manifesto against the Greek status quo, and was painted by a Greek. Spaniards, reasonably, dubbed him el greco.

Domenikos Theotokopoulos was born in Crete in 1541 and trained as an icon painter. Early in his career, he found the pictorial constraints of his craft irksome: the rebellious St Luke panel may have been painted when he was just 19. He was 25 or so when he left for Crete's ruling city, Venice, and a decade older when, via Rome, he arrived in Spain. For the purposes of the Kunstpalast's show, however, the year to keep in mind is 1912, when a collector called Marczell von Nemes showed his Grecos in Düsseldorf.

It is hard to imagine the disfavour into which the Cretan had fallen in Establishment circles. In 1881, the Prado's director moaned about having to store El Greco's "ridiculous caricatures", many of which were sold off. Sixteen years before, though, Edouard Manet had visited the gallery and been struck by the unfashionable artist. In Paris, he mentioned him to Cézanne, and ...

... and what, exactly? The Kunstpalast's curators are far too sensible to say anything so vulgar, but the answer, sort of, is: ... and Modernism. Cézanne may never have seen an El Greco in the flesh, but he saw plenty in reproduction. It is difficult not to sense the spatial organisation of works such as his great Laocoö* in Cézanne's Bathers at Rest of 1876-77. From there we fast forward to 1899 and a drawing by Picasso inscribed Yo, El Greco ("I, El Greco"). All of which suggests that Cubism may owe its preoccupation with flatness to a Byzantine painter who never quite rid himself of it.

This show is less concerned with what the French and Spanish made of El Greco than with his effect on German art. When, 100 years ago, Nemes's Grecos appeared in Düsseldorf, they were shown alongside contemporary works. The pairing was significant. If Cézanne was too dangerous for Germans to claim as an ancestor, El Greco – a genuine Old Master – fitted the bill. Painters were swept away by his odd perspective, avant la lettre Expressionism, and acid, Venetian palette. The Kunstpalast's show is full of works by Karl Hofer, Max Beckmann and Oskar Kokoschka which show signs of that moment, a century ago, when El Greco entered the German avant-garde imagination. In its quiet, reasonable way, the Kunstpalast rewrites the history of a strand of modern art.

It would be pretty well unthinkable for a contemporary artist to respond to Venice as El Greco did. Art, now, is about the ego, and nowhere more so than in the work of Urs Fischer, a 30-something Swiss-German who has what is known as a diverse practice, which means that he makes different kinds of work out of different kinds of things: candlewax, bronze, polystyrene, naked ladies, prayer, swinging lightbulbs, et cetera. His latest show is at the Palazzo Grassi in Venice, although it might be anywhere big enough to house it. Its centrepiece, the exact recreation of a London studio Fischer once had, gives the show its name. It is called, for reasons unexplained, Madame Fisscher.

Upstairs is a suite of works called Holes. Suspended by fishing twine, these include a polystyrene anus, mouth, ear, penis and nose. "Did ya notice there's no vagina?" hissed an angry American lady: I hadn't, actually. Perhaps this was meant to be provided by the naked female model who lay about the adjoining room.

Beyond that was a space full of brightly painted, floor-to-ceiling squiggles, like a Brice Marden in 3D. It may have been called Spinoza Rhapsody or A Thing Called Gearbox: the signage wasn't clear. Beyond that again was a life-size wax man in a tweed coat and slacks – Fischer has an itch for Madame Tussauds – which may or may not have been a candle. What to make of all this I do not know, although I feel on safe ground in saying that Urs Fischer's practice is very diverse indeed.

'El Greco and Modernism' (0049 211 8990200) to 12 Aug. Urs Fisher (00 39 041 2719039) to 15 Jul

Next week

Charles Darwent takes a shot at the Ashmolean's English Prize

Critic’s choice

The Bauhaus exhibition at London's Barbican goes for a wide-angled view on the art school, taking in colour charts, theatre costumes, party snaps, cool typefaces, teapots and modernist architecture on the way (to 12 Aug). An Edvard Munch pastel may have just sold for £74m, but you can enjoy his graphic works for a lot less at the Scottish National Gallery of Modern Art (to 23 Sep).