Theatre / Mother Courage - Royal National Theatre, London

It's notable how often people tell you that, above all, Brecht should be entertaining. Partly that's a reaction to a long British tradition of regarding anything German as humourless and didactic - honest, they're saying, you'll enjoy this. But it's also a reaction to Brecht himself: a recognition that the sheer weight of ideas in his plays pushes you towards an intellectual rather than emotional appreciation of them; it's easy to be aware of the logic of the thing, rather than how well it works as a piece of theatre.

You can see this effect at work in Jonathan Kent's production of Mother Courage. It's plain that Kent has set out to present a big night of entertainment - big stage, big music, big symbols (a giant eagle flies round and round above the action), big cast, big names (Michael Gough wheeled on for a two-minute cameo); and the result is a gripping evening. But it is, despite his best efforts, largely an intellectual grip that it exerts - at the end, when the last of Mother Courage's children has been killed and she's left to pull her cart alone around the battlefields of Europe, you find yourself sitting back and thinking, "Well, that was fascinating."

The most fascinating part is, naturally, Diana Rigg's brilliantly argued Mother Courage. In a clear-eyed programme note, David Hare (who has written this version from a literal translation by the excellent Anthony Meech) argues that it's a mistake to see Courage as having a sort of "peasant" wisdom. For a start, she's no peasant but rather, a petit bourgeois, a successful trader; and in any case, what she offers is the wisdom of someone who is naturally brilliant. Rigg embodies this idea of Courage to a tee: fast-talking, stroppy, with an intimidating mannishness in the way she stands with her arms akimbo and her jaw jutting - you could imagine Bet Lynch would have turned out something like this if she'd been around for the Thirty Years War.

At times, though, you do feel that she's arguing a little too hard - a woman trying to carry on her business and protect her children in wartime would be a little more ingratiating than this. It's necessary for Courage to be tough-minded, because the message is that even the toughest can't win in a war; but because she's so hard, you can't quite believe in the final calamity. What she needs is a smidgen of the wheedling hopelessness that Geoffrey Hutchings, as the Cook who hitches up with Courage, brings to his performance of "The Song of Solomon" - the play's comic highlight.

Still, if emotion is lacking in the centre of the play, there's plenty of it elsewhere - in Jonathan Dove's clever Kurt Weillish score, in Lesley Sharp's performance as Courage's dumb daughter Kattrin, miming her heart out. And the casting is mostly impressive - with worthy contributions from David Bradley as the disillusioned chaplain, and Doon Mackichan's tarty Yvette. It's not the most involving Mother Courage, but it is highly polished and bursting with intelligence. On the whole, you'll enjoy this.

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ROBERT HANKS