There was a concept a long time ago that you would do a different type of reactor called a "fast reactor," that would make a bunch of another element called plutonium, and then you would pull that out, and then you would burn that. That's called "breeding" in a fast reactor. That is bad because plutonium is nuclear weapons material. It's messy. The processing you have to get through is not only environmentally difficultly, it's extremely expensive.

Software suppliers are trying to make their software packages more 'user-friendly'... Their best approach so far has been to take all the old brochures and stamp the words 'user-friendly' on the cover.

Taking a look back, one big reqret is, I left Harvard with no real awareness of the awful inequities in the world. The appalling disparities of health and wealth and opportunity that condemned millions of people to the lives of despair. I learned a lot here at Harvard about new ideas and economics, and politics. I got great exposure to the advances being made in the sciences. But humanities greatest advances are not in its discoveries, but in how those discoveries are applied to reduce inequity.

I meet people overseas that know five languages - that the only language I'm comfortable in is English.

Don't wallow in failure. Instead, learn from it.

The Gates Foundation has learned that two questions can predict how much kids learn: 'Does your teacher use class time well?' and, 'When you're confused, does your teacher help you get straightened out?'

It was really phenomenal [Warren Buffett donation]. It grew out of the friendship that we had and the fact that his plan to have his wife run the foundation and give things away changed when she tragically died.