Eigen spent his early childhood during the war in Berlin and in Czechoslovakia where his father had been assigned by the Nazi regime to manage a large factory.
His time on the American continent was the opportunity for a four-month life-changing road-trip through Latin America where he developed his awareness for social injustice and human rights.
In 1971 he took a two-year leave to provide under Ford Foundation sponsorship for legal and technical assistance to the government of Botswana focusing on natural resources development.
Over the years at the World Bank, Eigen realised how much his work was being dwarfed by the devastating effects of corruption, which in fact he found to be the main obstacle to economic, social and democratic development.
Further compelled by the recurring robust breakfast discussions with his wife Jutta, who had been providing medical care to the poorest in Kenyan slums, Eigen started considering the tackling of corruption as a vital goal of his work at the World Bank.
Since most developed country governments condoned the active bribery by their citizens outside their borders, his efforts were met widely dismissed as naïve and even with hostility – including in Germany.
Out of their kitchen, Eigen continued to marshal friends and other supporters to found an organisation to tackle corruption, originally to be called “Business Practice Monitor (BPM)”.
Only after numerous workshops and conferences a concept emerged in the development community and among civil society that recognised the key responsibility of business for bribing decision makers in often fragile countries.
In February 1993 Eigen gathered some 20 inspired like-minded and experts from around the world in the Hague Netherlands where they signed the Founding Charter of Transparency International in the office of the Dutch Development Minister Jan Pronk in front of a German Notary, for it to become a charitable society based in Berlin.
In May of the same year Eigen had managed to secure funding from the GTZ and the German Development Foundation (Deutsche Stiftung für Internationale Entwicklung (DSE)) to publicly launch TI in the Villa Borsig, the official Guest House of the Government in Berlin-Tegel, having mobilised for that occasion numerous leaders from Africa, Asia and Latin America as well as the German development community establishment.
As Eigen likes to explain, this saw rich countries criminalising overseas corruption which they used to practically sponsor by allowing the deduction of foreign bribery as another business expense.
This conciliating approach earned him soon a standing invitation at the World Economic Forum in Davos, where he represented TI and was the first civil society leader participating as such.
Eigen in turn advocated for WEF to open their doors wider to NGOs, paying the way for Amnesty International, Greenpeace or Save the Children to participate.
In 1979/80 Eigen taught as guest professor at Johann Wolfgang Goethe Universität, Frankfurt/M, for the winter semesters of 1999 and 2000 at Harvard University, and in 2001 at Johns Hopkins School of Advanced International Studies (SAIS).