I've been studying how quickly we can get energy out to the poor countries - a lot of which are in Africa - and how little progress we've made there. There's no more electricity today in sub-Saharan Africa per person than there was 20 years ago.

If you mess up, it's not your parents' fault, so don't whine about your mistakes, learn from them.

You may have heard of Black Friday and Cyber Monday. There's another day you might want to know about: Giving Tuesday. The idea is pretty straightforward. On the Tuesday after Thanksgiving, shoppers take a break from their gift-buying and donate what they can to charity.

All lives have equal value. And so you say, 'why do poor children die when other children don't? Why do some people have enough nutrition or reasonable toilets and other people don't?' So those basic needs that, through innovation, actually it's very affordable to bring them...to everyone.

I think when smallpox was eliminated, the whole world got pretty excited about that because it’s just such a dramatic success.

In the same way that when the car got going, people thought it would be an electric car, people thought it would be a steam car. Actually, the dark horse in that race was internal combustion, but because of the energy density of gasoline and discovery of oil in large amounts at that point in first Pennsylvania and then Texas, it won out over those other two, to the point that those other two are actually viewed as obscure footnotes in history.

The only definition by which Americas best days are behind it is on a purely relative basis.