If... many influential people have failed to understand, or have just forgotten, what we were up against in the Cold War and how we overcame it, they are not going to be capable of securing, let alone enlarging, the gains that liberty has made.

Do not overrate what you have received, nor envy others. He who envies others does not obtain peace of mind.

A civilization which leaves so large a number of its participants unsatisfied and drives them into revolt neither has nor deserves the prospect of a lasting existence.

There's no guarantee that the United States will be around 200 years from now.

Darwin's theory of evolution is a framework by which we understand the diversity of life on Earth. But there is no equation sitting there in Darwin's 'Origin of Species' that you apply and say, 'What is this species going to look like in 100 years or 1,000 years?' Biology isn't there yet with that kind of predictive precision.