The Rothschilds have a maxim which helps to explain why they have been in business for so long and so successfully: "Tops and bottoms are for fools and madmen." David Cameron would agree. Over the summer, while Labour was rejoicing and Tories were in despair, Mr Cameron was as cool as a glass of Pimm's. Now, when everyone tells him that victory is assured, he swiftly reminds them that prices can fall as well as rise. No one can benefit so much from volatility without also fearing it.
When Roman generals had a triumph, the Eternal City was given over to panoply and feasting. But there was one discordant note. A lictor would be stationed near the hero of the hour, with the duty of whispering in his ear: "Remember you are mortal". On the day that Mrs Thatcher became PM, Michael Onslow, that learned and independent-minded Tory peer, sent her a letter of congratulations which also advised her to heed the lictor's warning. He received a charming reply, with the promise that she would not forget the lictor. She promptly did.
David Cameron knows better. He should, for he has already witnessed a great deal of mortality: Norman Lamont, John Major, Messrs Hague, Duncan-Smith and Howard, sundry Liberals barely worth counting among the ground game, and finally, Tony Blair and Gordon Brown. Although Mr Brown is not dead yet, he resembles a bull in the final stages of the corrida: blood-boltered, shoulders festooned with picadors' darts, waiting for the merciful quietus of the matador's sword (that said, David Cameron would need no reminding that many a matador has been gored by a dying bull).
Mr Cameron can draw on far more political experience than his youthful appearance would suggest. Despite his guileless manner, this is also a man who believes in thinking and planning. In October 2005, when it had become clear that Mr Cameron would win the leadership, I talked to a senior figure from the Major era. We agreed that by December, when the formalities were completed, David Cameron would be exhausted. So would those around him. They would not know what to do next. There was a grave risk that Tony Blair would exploit this. Mr Cameron might lose some early battles, thus discrediting his leadership before it had begun. So the two of us tried to work out how to help.
What nonsense: probably the silliest political misjudgement that I have ever made. David Cameron and his close advisers never stopped planning their next few moves. They are not as obsessed as Alastair Campbell, who could not watch Accrington Stanley play Clogthorpe Academicals without wondering whether there was anything in the game that he could use to stuff the Tories. But like Alastair, the Cameroons know that you are either setting the political agenda or having it set against you.
At this moment, there might seem little reason for the Tories to worry. A couple of weeks ago, David Cameron appeared to have a nagging problem, and Gordon Brown an unexpected advantage. However badly the Government did, the Tories were not moving above 40 per cent, while Labour MPs who ought to have been panicking were still behaving like a remarkably stoical cartload of prisoners on their way to the cells in Newgate to the gallows at Tyburn. Recently, however, Mr Cameron has moved up to 45 per cent a useful Christmas present while the first snowdrops of discontent are pushing through the dead soil of Labour dreams.
Even so, there is no scope for complacency. A couple of years ago, I went to a jolly point-to-point. Coming over the last fence, one jockey was well in front. He took a long, leisurely, almost gloating look over his shoulder, and promptly fell off. That is not an example to follow. Instead, the Tories ought to be concentrating on the main electoral obstacle which still lies between them and victory. Although this might seem the wrong season to make the comment, Mr Cameron and his colleagues have a problem with tone. They sound too cheerful.
The late Gordon Reece, one of Mrs Thatcher's principal advisers, had a quality which distinguished him from most of the PR men who pose as experts on public opinion. He was genuine. Gordon had a licked-finger-in-the-wind, intuitive understanding of the popular mood. He once asked a group of Tories why the late Princess of Wales had such a hold over so many people. Various explanations were offered and politely dismissed before Gordon answered his own question. "Most people are unhappy. They may not lead lives of quiet desperation, but they are chronically dissatisfied with their circumstances, and slightly ashamed of themselves for being so. Then along comes Diana, as beautiful as a girl could be, with all the money a girl could spend. She is a Princess; she has everything yet she is unhappy. Diana was the patron saint of unhappiness who made all the other sufferers feel vindicated."
Though no one is suggesting that Mr Cameron should emulate her, he needs to find a political body language which will appeal to those who feel that they are having a tough time in a hard world. It is natural for politicians to deal in optimism, which is just as well for David Cameron. If gloom won elections, Gordon Brown would be in power for ever and ever. But the Tory leader ought to try to imitate that marvellous politician and president, Ronald Reagan. Especially in contrast to the misery-gutted, mean-spirited Jimmy Carter, Mr Reagan made Americans feel good about themselves and hopeful about their future. Yet he also persuaded Hank Hardhat and Joe Sixpack that he knew what it was like for them. Without ever descending anywhere near snarling populism, he was able to make them feel that he understood their discontent. David Cameron has to do something similar.
Bloomsbury might seem an odd literary reference in this context, but there is abiding wisdom in Forster's "only connect". It takes political skills of a high order to connect the anger of the Tory lower-middle classes with grand intellectual ambitions to reform government and the public services. But no one should doubt Mr Cameron's skills.
Not all Etonians possess them. In 1922, when Bonar Law resigned, Lord Curzon was staying in a house without a telephone, so he had to be summoned to London by telegram. Assuming that he was about to become Prime Minister, he spent the train journey drawing up his cabinet. But George VI's private secretary broke the terrible news. He was not to be PM. Curzon was heartbroken. The distress may have shortened his life.
This might seem to teach politicians a lesson; if you count chickens before they are hatched, you will turn into a turkey. Despite that risk, David Cameron ought to spend a lot of the next two years preparing for government. For the moment, however, he and his party are entitled to enjoy Christmas.