He was certainly one of the great men of the 20th century, one of the
few who were able to change the course of the world. He did this by
creating new ideas, by implementing them himself but more often by
convincing others to bring them to effect.
The World Wildlife Fund (today World Wide Fund for Nature, WWF) was
mainly his idea, although he did not become a member of the board but
did convince Sir Peter Scott and others to put it into practice.
Personally, I was much encouraged by him and François Bourlière to
undertake project MAR, the first European project for wetland
conservation which resulted in the Ramsar convention and other
scientific and awareness programmes for wetlands.