I think one of the great dangers here is going and categorizing anybody from one religion as a terrorist. That's not true... That would let the terrorists win. That's what they want us to do.

The truth of the matter is: you can create a great legacy, and inspire others, by giving it to philanthropic organizations.

Government should not tell you what to do unless there's a compelling public purpose.

If you really believe that you're making a difference and that you can leave a legacy of better schools and jobs and safer streets, why would you not spend the money? The objective is to improve the schools, bring down crime, build affordable housing, clean the streets - not to have a fair fight.

The fact is, the most painful and tragic lesson of the 20th century was that regimes based on racial superiority and religious hatred can't be trusted to keep their word to the international community.

Fifty percent of the world's population lives in cities. In a couple of decades, 70 percent of the world's population will be living in cities. Cities are where the problem is. Cities are where the solution is, where creativity exists to address the challenges and where they have most impact. This is why, in 2005, the C40 was founded, an organization of cities that address climate change. It started with 18 cities; now it's 91. Cities simply are the key to saving the planet.

When I came into office, people said, 'Billionaire? How do they live? What do they eat? How do they sleep?' Today, they see me on the subway coming uptown. A couple of people say hi, some people smile and nod. Some people just sleep. It's not an issue.