Engineering professor Li Guohao smiled when he saw a framed portrait of Wan Gang in a hallway at the Audi headquarters in Germany. It was his last trip abroad, and Dr Wan, one of Professor Li's favourites at Tongji University, was showing him around the rarefied surrounds of his workplace. They had last seen each other 15 years beforehand, before Dr Wan began his climb through the company, from the production line to the research laboratory and on to strategy meetings. But when the trip in 2000 was about to end, Professor Li, 83, asked Dr Wan a question. 'I am very pleased to see that you have done really well in Germany and you are in the prime of your career,' he said. 'But very soon you will have to face some important transitions in your life. 'You could either continue to work hard and move up a step or return to the university and become a professor. 'China is also entering a prime time of development, with some big transitions taking place at the fundamental level. I know you have your own ambitions for the automobile industry. 'In which country do you think there are more space and opportunities?' Dr Wan hesitated. He had always respected the professor who, more than half a century before, had left Germany for the mainland to build a dozen landmark bridges, including the first over the Yangtze River. He found the question - and the decision - difficult, but opted to return to China. Dr Wan is now China's minister of science and technology. He hopes the hundreds of thousands of mainland scientists and researchers working and living abroad will make the same choice. He says this not as a central government official, but as someone who has gone through all the ebbs and flows of returning home. The mainland would have remained a rural society without expatriates returning from overseas. Thanks to a homeward rush in the early 1950s, the return of some of the world's leading physicists, chemists, rocket experts and engineers helped the nation to establish modern industry, trigger its first nuclear bomb and even send a satellite into space. The door was shut in the 1960s during the Cultural Revolution. But since the reopening policy in the late 1970s, more than 1.2 million of the most talented mainland students have set their sights on studying and working overseas. Only a quarter had returned by last year, according to the Ministry of Education. But Dr Wan said there was a new movement to head back to the mainland among the hundreds of thousands of Chinese who have become wealthy, successful and even leading figures in their fields overseas. 'When I became the president of Tongji University in 2004, people joked that I was the first overseas returnee entrusted with a university; but now I can just ask them to look around and tell me which university's president is not a returnee after a long or short stay overseas,' he said. 'After I became a minister, I talked to other ministers in the State Council and found that many of them had spent at least a year studying or working overseas; many of them obtained their PhDs outside China ... The number of returnees is increasing, with over 60,000 in 2006. I think it will go up substantially this year.' There is a strong intellectual stimulus to return: the mainland is the world's biggest manufacturing engine and wants to compete in some high-end sectors such as information technology, life sciences and new materials that are, so far, dominated by developed countries. But not every Chinese overseas was ready to give up things they had worked so hard to earn, Dr Wan said. 'It is very difficult to persuade the family [to return], especially when you are in a thriving environment,' he said. 'It is not that you return because you encounter difficulties. It happens when your career is on the rise and you must give up a lucrative job. 'To be honest, living standards overseas are higher, the income is more stable, the research environment in big corporations is superior and you can make full use of your talent and become a highly respected member in the company. 'Many overseas Chinese are doing great because they are extremely hard-working - they are willing to make sacrifices, with the patience to move up step by step in the most competitive environment. 'Then why are there so many people, including myself, coming back, giving up a higher income, a higher living standard and a better environment? 'From my personal experience, it happens naturally when you reach a certain stage in life. 'When you have just moved overseas, you are struggling for material well-being and stability. 'But once you have established a foundation, wealth is not the biggest issue. 'The biggest issue is how to find the pleasure in your career.' Dr Wan said the mainland was one of the world's fastest developing areas, and its leaders take science and technology very seriously. In the past five years, growth in government investment in research and development has consistently outpaced the growth of the gross domestic product. The total investment in 2006 reached 300 billion yuan (HK$343 billion). Last year, spending increased by more than 60 billion yuan. But it is not only money that matters. 'In the past three decades, China has focused almost entirely on economic development. Now the emphasis is changing to so-called 'scientific development'. 'When I went overseas, people often asked me what 'scientific development' meant,' Dr Wan said. 'It simply means that the kind of development we want would be complete, co-ordinated and sustainable. 'We are also building a society that aims to have harmony between nature and people, among different regions and between an individual and society ... We are at a period of transition.' Many Chinese who have stayed in developed countries would find that their expertise would earn them greater success on the mainland, he insists. 'Dr Shi Zhengrong, the president of Suntech, came back from Australia and built up the world's largest solar-panel empire in just a few years,' he said. 'Dr Wang Xiaodong, the head of National Biological Sciences, returned with more than 30 researchers and they published more than 30 papers in the world's top academic journals last year, including six for Nature and Science. 'I also have a good classmate who worked for Intel in the US, but now has returned to a joint venture production plant, taking charge of production in Shanghai.' Dr Wan said most of the opportunities were not directly created by the government, but by the huge market and demand on the mainland. 'The representatives of nearly 50 Fortune 500 companies had a meeting with me and expressed their eagerness to set up research facilities and attract talent,' he said. 'Therefore, China has good potential to become the world's research centre.' Last year, the nation's 54 hi-tech industrial zones generated a total output of more than 5.5 trillion yuan, with per capita output of more than half a million yuan. More than 80 per cent of these companies - specialising in information technology, telecommunications, pharmaceuticals, medical equipment, new energy and environmental protection - have been created by people returning from overseas. In return for coming back, the authorities have offered various incentives. 'They will receive resettlement benefits once they join a research institute,' he said. 'If they want to start up a company, the government and the banks will give them special treatment. 'Even if they no longer hold Chinese nationality, they can still head up some key national science and technology programmes. 'In some provinces, the policies may be more accommodating. 'But some underlying issues remain: some still have trouble finding appropriate schools for their children; some spouses remain unemployed for years; social and medical insurance can be improved; some have changed their nationality, and their interests should be stressed and protected.' Dr Wan said he was working on these issues and was taking them very seriously. 'Making policy is like car design ... we must always think from the perspective of the passenger's safety, comfort and convenience,' he said. 'Many things are very small; but they are often quite effective.' Dr Wan has some last words for overseas returnees. 'Our country is now on the fast development track, and sometimes some changes take place more quickly than elsewhere. 'You can seize the opportunity, and I believe that many problems can be solved in the course of development.'