Most things are difficult at the beginning and they become fun, something you love, only after you've worked at them.

Once you get to the Enlightenment, the way that powers get to be hyperpowers isn't just by conquest. It's through commerce and innovation. Societies like the Dutch Republic and the United States used tolerance to become a magnet for enterprising immigrants.

Genghis Khan decreed religious tolerance for all of his conquered peoples. So I think he definitely would approve of our constitutional protections of freedom of religion. I think he would also approve of the way the U.S. has been able to attract talented people from all over the world.

My youngest sister, Cindy, has Down syndrome, and I remember my mother spending hours and hours with her, teaching her to tie her shoelaces on her own, drilling multiplication tables with Cindy, practicing piano every day with her. No one expected Cindy to get a Ph.D.! But my mom wanted her to be the best she could be, within her limits.

The most successful hyperpowers are the ones where there was actual intermixing. Tang dynasty China was Chinas golden age, and contrary to what I was told when I was growing up, Tang China was founded by a man who by todays standards was no more than half Chinese. It was a mixed-blood dynasty that pulled in "barbarians" from the steppe.

Nothing is fun until you're good at it.

Parenting cannot just be one size fits all.