Sir

John Dowling1 pays a well-deserved tribute to George Wald's great contributions to the chemistry of vision.

Wald was also concerned with the disappearance of human beings. He said, in 1975, that he found it difficult “to see how the human race will get itself much past the year 2000”.

Warming to his subject, he could find no reason to believe that his children and his students would “be in physical existence ten, twenty, twenty-five years from now”2. In short, “…life on earth may end as early as 1985”3. I am not aware that he retracted this statement.