"As its name implies, World Wildlife Fund is in the business of raising money for the conservation of nature and to that end Fleur Cowles — a long time and dedicated supporter of the Fund — has offered a proportion of the royalities from the sale of this book to WWF. It is easy enough to feel an affinity to a particular species of animal, but I just wonder what it would be like to be reincarnated in an animal whose species had been so reduced in numbers that it was in danger of extinction. What would be its feelings towards the human species whose population explosion had denied it somewhere to exist and by sheer indifference had destroyed any chance of it finding a mate and producing a family? There are not just a few such species, there are a great many and the list is getting longer every day. When I look at the shelf with all the volumes of the Red Data Books listing endangered species I must confess that I am tempted to ask for reincarnation as a particularly deadly virus, but that is perhaps going too far. I would much rather see the human species voluntarily restrict its numbers out of consideration for the rest of the living world with which it still has a chance of sharing this planet."