Till now, mankind has either taken it as a matter of course that it is going to survive, or, alternatively, assumed that its destiny will be decided by forces beyond human control: the gods or God or Nature. We have now woken up to the truth that, today, we are in greater danger of extinction than we have been at any time since the date —perhaps 30,000 years ago—at which our ancestors gained the upper hand over all other forms of life on this planet except microbes and viruses. In the present age we have discovered and conquered the microbes, and we have hopes of getting the better of the viruses. But our recent victories over non-human menaces to human life are far outweighed by new threats to us from ourselves. These threats have no precedents; for man, armed with the power of science applied to technology, is a vastly more formidable enemy for man than any non-human enemy that man has yet encountered.