Visual Arts: A little of what you fancy

Why join the queues? Try two small shows at the National Gallery: Gentileschi and Van Der Weyden.

The blockbuster problem. It's not just the crowds. It's the fact that the crowds can only be pulled by offering many more pictures than any viewer could possibly look at within the space of single visit, even if the exhibition was entirely deserted. If you think about it, the crowds actually provide a convenient diversion from this fact. They mask one impossibility (excess of art) with another (excess of viewers). The crush of people, making much of the show invisible, disguises the fact that it would be unviewable anyway. Why call it a problem? It works out very well.

And the smaller, fully viewable show, the one with say 10 or 20 pictures? It's pretty much the ideal thing, I would have thought. Ideal, I mean, for the general viewer. Because the sharpest irony of blockbusters is that their real beneficiaries aren't the public crowds at all, but rather the scholars, the art-historians - the people who genuinely need to see all those Monets or Bonnards altogether, and who will go keep returning, out of hours, to do so.

On the other hand, to say "here's a show where you can see, and really see, six extremely good paintings", however good advice, is never going to get feet moving in large numbers. Just as well, I suppose. But if six extremely good paintings is your idea of fun, try the small Orazio Gentileschi exhibition at the National Gallery.

Orazio (that's to say, Horace) Gentileschi. It's not a household name. Italian painter, 1563-1639. He was Artemisia's father, and she's now the more famous, being widely rated as the top woman European painter of all time. Orazio was the friend and close follower of Caravaggio (he lent Caravaggio a set of wings used for doing angels and cupids). Late in life, he left Italy to spend his sixties and seventies in England, working for the court of Charles I. The dozen pictures here, assembled from Dublin, Birmingham, Hampton Court, Bilbao and Madrid, are partly from those years. He is a terrifically interesting artist.

He's a great painter of physical awkwardness. That may sound like dubious praise - an optimistic or pretentious way of saying that he was simply a clumsy painter. I overheard a couple of other visitors voicing just that view. They were looking at Gentileschi's Finding of Moses, a crowded group scene, and saying it was terribly stiff and artificial, and Veronese does this sort of thing much better. And with these Moses pictures (there are two versions here), I kind of agree. The compositions do rather stumble over themselves.

But generally I don't agree. The clumsiness is the point - the moral point. These pictures tell Bible stories, and the idea is to give the stories a kind of realism. It's not a realism like Caravaggio's, where saints are represented as horny-handed sons and daughters of toil. Gentileschi's people are, relatively, ladies and gents. His realism is not to do with social class so much as with the nature of events. The way he arranges bodies in a picture is a way of insisting that great moments of sacred history were not enacted with decisive gestures in elegant and well-blocked tableaux. They happened awkwardly. His awkwardness is judged.

Look at the first scene in the show, David Slaying Goliath (1605-8). The fallen giant and the little man wielding the giant's huge sword are crammed inside the picture frame as if inside a box. See how the tip of the blade and the tip of David's pinky precisely touch the picture's edge, and the giant's raised hand is just short of it, and his foot just overlaps - very difficult, one feels, to swing that unwieldy weapon in this confined space. There's bodily confusion, too. There's a non-specific bit of flesh that's probably the giant's elbow, but might well be his knee. His other knee seems to merge into David. And there's an odd, discordant echo-cum- jump in the way that Goliath's defensive left-hand gesture is repeated exactly, small-scale, in David's own triumphant left-hand gesture. The general effect is to turn a heroic victory into one of those wrestling bouts where you're unsure which limbs are whose.

The next picture is another cracker, utterly bizarre. The Rest on the Flight into Egypt (c 1615-20): I suppose one should resist the temptation to call it "surreal", but the temptation is certainly strong. Alternatively, one might speculate that Gentileschi was making propaganda for an obscure donkey cult. It is the donkey's head that presides over this scene. The holy family lie below the picture's halfway mark. Behind them, flat across the picture, runs a stretch of crumbling plastered wall. Behind that, above them, central, enormous, the donkey's profile pokes out - quasi- framed by the broken brickwork, isolated against the clouds. The moke is god.

What is going on? I think nobody has a clue. The show's small catalogue doesn't acknowledge how strange this image is, let alone explain it. There is a possible echo between the donkey's head poking from behind the wall, and the Virgin Mary's breast - she is suckling Jesus - peeping out (in the same direction) from her dress, but I'm not sure what the implied simile would be.

All one can say is that a lop-sided sense of significance is another aspect of Gentileschi's awkwardness. As, for instance, in Lot and his Daughters (1629). Here, a disproportionate amount of attention is given to a beautifully rendered vine plant. It commands about a third of the picture surface. You may say that this is the vine that made the wine with which the girls got Lot drunk so that they could have sex with him (in order to repeople the land after the destruction of Sodom and Gomorrah). But put like that, you can see that the vine is not the obvious point of emphasis in this narrative. Perhaps it's another, purely pictorial analogy, the twining vine figuring the tenderly intertwined limbs of the sleeping Lot and daughter, with some more clever limb echoes and confusions.

Meanwhile, in Joseph and Potiphar's Wife (1630-2), what would normally be a scene of sudden action, a man escaping a woman's pounce, is converted into dreamlike slow-motion. There's a fantastically painted spread of hanging scarlet drapery, and an oddly significant lump of pillow, and Joseph striding from the room, away from the viewer, is done with cunning spatial ambiguity, so his body seems to be at several distances. I hope this is recommendation enough. The show is free, and when I saw it, there weren't many there.

The National Gallery has another, even smaller exhibition, of pictures by that exquisite old Flemish master, Rogier van der Weyden, one of the first generation of oil painters. The focus of the show is the re-uniting of the National's own Magdalene Reading with two other fragments of the altarpiece to which it originally belonged. But the real revelation for me was the amazing quality of the photo-reproduction.

One the two surviving bits, on loan from Lisbon, actually fits on to the Magdalene fragment, and to demonstrate this, the show has made actual- size photos of each, stuck them on actual-width board, and re-assembled them, beside their originals. Now I don't say that photo and painting are indistinguishable. Side by side, you can see the difference clearly enough, chiefly in relative luminosity. But the difference isn't that large. The colour is extraordinarily close. I'm not sure, with just the photo and no tip-off, how long it would have taken me to spot the truth. And this of course suggests a simple answer to the over-crowded blockbuster. Three or four of everything.

National Gallery, London WC2 (0171-747 2885); daily, free. Gentileschi to 23 May; Van der Weyden to 4 Jul