You are capable of more than you know. Choose a goal that seems right for you and strive to be the best, however hard the path. Aim high. Behave honorably. Prepare to be alone at times, and to endure failure. Persist! The world needs all you can give.

Biological diversity is the key to the maintenance of the world as we know it... Eliminate one species, and another increases to take its place. Eliminate a great many species, and the local ecosystem starts to decay.

Women are extraordinary in lacking the estrus, or period of heat. The females of most other primate species become sexually active, to the point of aggression, only at the time of ovulation. Why has sexual responsiveness become nearly continuous? Unusually frequent sexual activity between males and females served as the principle device for cementing the pair bond.

The price of these failures has been a loss of moral consensus, a greater sense of helplessness about the human condition. ... The intellectual solution to the first dilemma can be achieved by a deeper and more courageous examination of human nature that combines the findings of biology with those of the social sciences.

We don't even know what species are out there, for the most part, particularly when you get down to the microbes and very small invertebrates. They make up the mass of the organisms around us, including the soil we depend on, the soil of cornfields as well as hardwood forests. We haven't taken ecology to the point where we can even make a crude prediction of what's going to happen when we've reduced the living world down to a certain level.

I think we will make it. Because one quality people have - certainly Americans have it - is that they can adapt when they see necessity staring them in the face. What to avoid is what someone once called the definition of hell: truth realized too late.

The great challenge of the twenty-first century is to raise people everywhere to a decent standard of living while preserving as much of the rest of life as possible.