And I think when you look at the animal kingdom, that is one of the most remarkable things.

But I think the most important one is that London was this city of 2.5 million people, and it was the largest city on the face of the planet at that point.

My belief is that this will help us to build a more integrated world with more partners and fewer terrorists, with more productive citizens and fewer haters, a place we'd all want our kids and our grandchildren to grow up in.

Now, I don't know about you guys, but judging the circumstances, right, any judge in the whole world, would look at the statistics and the evidence, and they would find any government of old guilty of child abuse. That's my belief.

You can talk about creationism which I think wouldn't go down well with this audience, at least not from a view where you were a proponent of it or you can talk about optimisations, spelled the British way, with an S, instead of a Z.

And that's probably because that's when everybody got aware of the environment and Earth Day and all the stuff that happened in the '60s with the Hippies and everything really did, I think, have an affect on global awareness.

So I decided instead, I would talk about someone who I think has done as much to make Americans happy as perhaps anyone over the last 20 years, a man who is a great personal hero of mine someone by the name of Howard Moskowitz, who is most famous for reinventing spaghetti sauce.

So, having seen all of this in the course of a 30 year career, I was still a skeptic about climate change until about 10 years ago, because I thought the story of climate change was based on computer models.

Because if architecture is what I believe it to be, which is the built form of our cultural ambitions, what do you do when presented with an opportunity to rectify a situation that represents somebody else's cultural ambitions relative to us?

No, what I want to do is take you back to 1854 in London for the next few minutes, and tell the story in brief of this outbreak, which in many ways, I think, helped create the world that we live in today, and particularly the kind of city that we live in today.

If you don't grow, you're what? If a relationship's not growing, if a business is not growing, if you're not growing, it doesn't matter how much money you have, how many friends you have, how many people love you, you feel like hell. And the reason we grow, I believe, is so we have something to give of value.