I don't measure success in numbers, but I consider my contributions of more than $1.3 billion to various causes over the years to be one of my proudest accomplishments and the best investment I've ever made. Those dollars have improved lives, saved species, fought disease, educated children, inspired change, challenged ideas and opened minds; at the time of my death, virtually all of my wealth will have gone to charity.

The United States has got some of the dumbest people in the world. I want you to know that we know that.

The happiest people are those who are contributing to society.

I regret that I wasn't more successful with my marriages, but it is what it is.

When I got my statement in January, I was worth $2.2 billion. Then I got another statement in August that said I was worth $3.2 billion. So I figure it's only nine months' earnings, who cares?

Over a three year period, I gave away half of what I had. To be honest, my hands shook as I signed it away. I knew I was taking myself out of the race to be the richest man in the world.

I'd like to say that right now, in the last few years, the Democrats have been closer - have been more pro-environment. The coal industry is pretty well entrenched in the Republican Party and that's one of the things that we need to phase out.