It simply doesn't make any sense for us to have illegal aliens in our custody in our courts and then let them go back to living here illegally. That's wrong and we should stop it.

History will remember Nelson Mandela as a champion for human dignity and freedom, for peace and reconciliation.

Sincerity? I can fake that.

Globalisation is not something that we can hold off or turn off. It is the economic equivalent of a force of nature, like wind or water.

When we got organized as a country and we wrote a fairly radical Constitution with a radical Bill of Rights, giving a radical amount of individual freedom to Americans, it was assumed that the Americans who had that freedom would use it responsibly.

In science, if the last 50 years were the age of physics, the next 50 years will be the age of biology.

What we should be doing [in US] is accelerating every year our efforts to reduce our greenhouse gas emissions, have a cleaner energy future, have much more energy conservation. And this won't hurt anybody. This will create a new economy for America, if we've got the discipline to do it.