When Newsnight profiled John Redwood earlier this week someone had the good idea of adding Shakespeare to

When Newsnight profiled John Redwood earlier this week, someone had the good idea of adding Shakespeare to the roster of political commentators. It wasn't a stunning piece of erudition, when you think about it - after all, Cassius's "lean and hungry look" is the standard journalistic cliche of conspiracy. But even so, Shakespeare's description fitted the former Welsh Secretary with unusual aptness and there was a disproportionate thrill in hearing hours of prosaic speculation give way to poetry. Like any good quotation, it worked as an assertion that these events were grander than the moment and it made me wonder why politicians now make so little use of this free supply of intellectual ballast.

Some of the reasons are obvious - we live in an age when coinage is more respected than quotation, the newly minted more honoured than anything with a patina of age. Nor can politicians make any easy assumptions about the common cultural currency of their audience. Gladstone could allude to Homer - modern politicians have to make sure that their listeners don't think he's a columnist on the Daily Mail. Even so, it seems odd that they don't take advantage of the free ride more often. As far as I can discover, Mrs Thatcher only once resorted to the bard - being more given to the thoughts of Chairman Roberts and the odd line of inspirational doggerel. But in The Downing Street Years she reveals that she included a quotation from Measure for Measure in a reply to an industrialist who had written urging her to be cautious about Trade Union reform. She concluded with this: "Our doubts are traitors /And make us lose the good we oft might win, / By fearing to attempt." Bill was one of us, it seems. In his only Shakespearean reference President Reagan, generally more familiar with John Wayne than John of Gaunt, followed a similar tactic.

In a speech to the Conservative Political Action Fund, early in his second term, Reagan quoted the "there is a tide in the affairs of men" speech (Julius Caesar again). It was intended to charge his address with a sense of historical destiny and it clearly worked. The audience broke into applause, giving Ronnie the opening for an illuminating ad- lib "It's typical, isn't it. I just quoted a great writer, but as an actor, I get the bow." That goes to the heart of all political quotation - the calculated knowledge that credit hardly ever goes to the speechwriter. Both Thatcher and Reagan exploit Shakespeare, using him in the way that you might draw on a celebrity endorsement.Not all politicians are quite as complacent, or so indifferent to the poet's capacity for contradiction.

John F Kennedy's favourite Shakespeare quotation, according to Richard Reeve's recent biography, was very different in tone, a wry encapsulation of the limits of political power. "I can call spirits from the vasty deep," says Glendower in Henry IV. "Why so can I," answers Hotspur, "or so can any man;/ But will they come when you do call them?"Kennedy recognises what Reagan and Thatcher do not - that great poetry is master of many moments, not just a servant of one. Gladstone, living in an age when the act of quotation still had the force of moral authority to it, also knew this - that the best quotations are a tribute paid by the transitory to the permanent. A fine speaker himself, he once found himself next to Tennyson on a public platform and spoke with a humility inconceivable in contemporary politicians.