Leading article: A man with the drive and vision to change our world in different ways

The announcement by Bill Gates that he is gradually to reduce his role in Microsoft and give up all day-to-day involvement in the company from 2008 created shock waves far beyond the business world - and no wonder. The decision by the world's richest man to phase in his retirement - or as he put it, to reorder his priorities - truly marks the end of an era. It also offers a stunning example of personal forward planning.

Bill Gates is seen as the original software pioneer. As a geeky entrepreneur, he abandoned Harvard to found the company that grew into Microsoft. He subsequently spearheaded the advance of new-tech business on the US Pacific coast. His company, with its youthful share-holding millionaires and egalitarian outlook, defined the culture for new-tech industries. It was smart-casual in every sense.

But Mr Gates also set a standard for hard-driving business practices that brought him up against the might of, first, US anti-trust laws and then the European Union's competition authorities. Always headstrong and sometimes petulant, he did a deal with the US authorities that kept Microsoft intact. His ill-tempered argument with the European Union continues.

At least some of his fortune, it could be argued, derives from monopolistic behaviour that belongs more properly to an earlier, less law-governed and more freewheeling, age. Some may divine in his decision, as a youthful 50 year-old, to start the transfer of his company to new management a recognition that the best times have come and gone. The company is facing fierce competition, not just from the EU's legal challenge, but from open-source software, such as Linux, from a newly resurgent Apple, and from the inventive wizardry of Google. Microsoft may be installed in nine out of 10 of the world's personal computers, but the potential for selling software may be shrinking, even as demand for original content and new applications marches on.

Tinged with self-interest or not, however, Mr Gates' intention to spend more time with the charitable foundation he set up with his wife and father is a thoroughly laudable one. It is a move that stands to place him among the giants of American philanthropy and could set him on a pedestal next to the giant of them all, Andrew Carnegie. It would be a neat twist if, like the steel magnate, Gates came to be better known to future generations for the way he spent his money than for how he earned it.

There are reasons, of course, why philanthropy is so developed in the United States, not all of which reflect a unique national disposition towards generosity. The tax incentives for giving are considerable and offer a lesson for this country, where the tax breaks, for the donor at least, are more stingy. The comparative harshness of US society also leaves glaring gaps in state social provision that have traditionally been filled - if at all - by the magnanimity of individuals with a social conscience.

The Bill & Melinda Gates Foundation is sometimes criticised, unfairly in our view, for weighting its giving towards the poorest countries. In fact, as much as 40 per cent of gifts go to causes in the US, with an emphasis on opening opportunities for disadvantaged ethnic minorities. Abroad, the foundation has focused on supporting Aids research and measures to combat tuberculosis and malaria. Its approach shares with Microsoft a very 21st-century combination of originality and intellectual rigour.

Bill Gates says that his long-term vision is to improve the lives of millions of people across the globe. It is a dream that he, perhaps alone of the world's super-wealthy, has not only the means, but also the drive, the energy - and now the time - to realise.