The rays are diffuse, but the specks of light are unmistakable. Share prices are up sharply. Even after slipping early this week, two-thirds of the 42 stock markets that The Economist tracks have rose in the past six weeks by more than 20 per cent. Different economic indicators from different parts of the world have brightened. China's economy is picking up. The slump in global manufacturing seems to be easing. Property markets in America and Britain are showing signs of life, as mortgage rates fall and homes become more affordable. Confidence is growing. A widely tracked index of investor sentiment in Germany has turned positive for the first time in almost two years.

All this is welcome--not least because the slump has been made so much worse by panic and despair. When the financial system was on the brink of collapse in September, investors shunned all but the safest assets, consumers stopped spending and firms shut down. That plunge into the depths could be succeeded by a virtuous cycle, where the wheels of finance turn again, cheerier consumers open their wallets and ambitious firms turn from hoarding cash to pursuing profits.

But, welcome as it is, optimism contains two traps, one obvious, and the other more subtle. The obvious trap is that confidence proves misplaced--that the glimmers of hope are misinterpreted as the beginnings of a strong recovery when all they really show is that the rate of decline is slowing. The subtler trap, particularly for politicians, is that confidence and better news create ruinous complacency. Optimism is one thing, but hubris that the world economy is returning to normal could hinder recovery and block policies to protect against a further plunge into the depths.

Luminous indicators

Begin with those glimmers. It is easy to read too much into the gain in share prices. Stockmarkets usually rally before economies improve, because investors spy the promise of fatter profits before the statisticians document a turnaround. But plenty of rallies fizzle into nothing. Between 1929 and 1932, the Dow Jones industrial average soared by more than 20 per cent four times, only to fall back below its previous lows. Today's crisis has seen five separate rallies in which share prices rose more than 10 per cent only to subside again.

The economic statistics are hard to interpret, too. The past six months have seen several slumps, each with a different trajectory. The plunge in manufacturing is in part the result of a huge global inventory adjustment. With unsold goods piling up and finance hard to come by, firms around the world have slashed production even faster than demand has fallen. Once firms have run down their stocks they will start making things again and the manufacturing recession will be past its worst.

Even if that moment is at hand, two other slumps are likely to poison the economy for much longer. The most important is the banking crisis and the purge of debt in the bubble economies, especially America and Britain. Demand has plummeted as tighter credit and sinking asset prices have exposed consumers' excessive borrowing and scared them into saving more. History suggests that such balance-sheet recessions are long and that the recoveries which eventually follow them are feeble.

The second slump is in the emerging world, where many economies have been hit by the sudden fall in private cross-border capital flows. Emerging economies, which imported capital worth 5 per cent of their GDP in 2007, now face a world where cautious investors keep their money at home. According to the IMF, banks, firms and governments in the emerging world have some $1.8 trillion-worth of borrowing to roll over this year, much of that in central and Eastern Europe. Even if emerging markets escape a full-blown debt crisis, investors' confidence is unlikely to recover for years.

Policymakers must give themselves room to change course in the future. Central banks need to lay out the rules that will govern their exit from exotic forms of policy easing. That may require new tools: the Federal Reserve would gain from being able to issue bonds that could mop up liquidity. All governments, especially those with the ropiest public finances, should think boldly about how to lower their debt ratios in the medium term--in ways that do not choke off nascent private demand. Rather than pushing up tax rates, they should think about raising retirement ages, reining in health costs and broadening the tax base.

This weekend many of the world's finance ministers and central bankers will meet in Washington, DC, for the spring meetings of the IMF and World Bank. Amid rising confidence, they will be tempted to pat themselves on the back. There is no time for that. The worst global slump since the depression is far from finished. There is work to do.