When the citizens of Baltimore banded together to repel the British during the War of 1812, three in five were immigrants, and one in five was black - some were free, some slaves.

The most fearless hearts, the audacious dreamers, have always maintained a sense of optimism that often flies in the face of the available evidence.

When I was in Grade 9, there was an election for high school president, and one of the candidates told us that if we elected him, he would abolish homework. He promised this to the entire student body from the stage in the school gymnasium.

Gilles Duceppe avoids making campaign promises altogether so he can emphasize that his Bloc Quebecois has only one objective: to prevent Harper from forming a majority government.

The presidency of the United States is not some crown to be passed between two families.

We haven't had an agenda for American cities probably since at least Jimmy Carter. We have left cities to fend for themselves.

Senator Mikulski has done an outstanding job representing Maryland in the U.S. Senate for nearly 30 years.

I did not dedicate my life to making Baltimore a safer and more just place because it was easy.

There are people in whole parts of our cities who are being totally left behind and disregarded. They are unheard. They are told they are unneeded by this economy. And that extreme poverty breeds conditions for extreme violence.

The way forward is always found through greater respect for the equal rights of all.

Back on September 11, terrorists attacked our metropolitan cores, two of America's great cities. They did that because they knew that was where they could do the most damage and weaken us the most.

If any mayor reduced school funding by 33 percent and called it the 'Strengthening Our Schools Initiative,' I think they'd be excoriated.

We have to wrap this imperative of addressing climate change in a prosperity framework, and secondly we have to do a much better job of putting forward an American jobs agenda that's a match for the climate challenge.

I believe that the best way to campaign is one-on-one with people.

You can't forge a new sort of consensus, you can't forge public opinion, by following public opinion.

Progressive leaders always try to take action on the forward edge of that movement, movement toward greater respect for the equal rights of all.

If there is a thread that unites all of our work, whether it's in Iowa or whether it's in Maryland or whether it's among our young men and women in Iraq and Afghanistan, I believe that it's the thread of human dignity.

I go to the gym pretty regularly.

All of us, wherever we happen to stand on the marriage equality issue, can agree that all our children deserve the opportunity to live in a loving, caring, committed, and stable home, protected equally under the law.

Progress is a choice.

Extreme poverty is extremely dangerous.

In 2013, Maryland had the second highest job creation rate of any state in the Mid Atlantic region - faster than both Pennsylvania and Virginia.

Putting aside competitive interests for a new kind of collaboration, Maryland pioneered a real-time encounter notification service to alert primary care doctors when their patients are hospitalized.

The most important advances, the qualitative leaps, are the least predictable. Not even the best scientists predicted the impact of nuclear physics, and everyday consumer items such as the iPhone would have seemed magic back in the 1950s.

There is an ever-widening gap between what science allows and what we should actually do. There are many doors science can open that should be kept closed, on prudential or ethical grounds.

The stupendous time spans of the evolutionary past are now part of common culture (though maybe not in the United States Bible Belt, nor in parts of the Islamic world). Most people are at ease with the idea that our present biosphere is the outcome of four billion years of Darwinian evolution.

We are 'nuclear waste' from the fuel that makes stars shine; indeed, each of us contains atoms whose provenance can be traced back to thousands of different stars spread through our Milky Way.

Some global hazards are insidious. They stem from pressure on energy supplies, food, water and other natural resources. And they will be aggravated as the population rises to a projected nine billion by mid-century, and by the effects of climate change. An 'ecological shock' could irreversibly degrade our environment.

Maybe the search for life shouldn't restrict attention to planets like Earth. Science fiction writers have other ideas: balloon-like creatures floating in the dense atmospheres of planets such as Jupiter, swarms of intelligent insects, nano-scale robots and more.

If you take 10,000 people at random, 9,999 have something in common: their interests in business lie on or near the Earth's surface. The odd one out is an astronomer, and I am one of that strange breed.

During the 20th century, we came to understand that the essence of all substances - their colour, texture, hardness and so forth - is set by their structure, on scales far smaller even than a microscope can see. Everything on Earth is made of atoms, which are, especially in living things, combined together in intricate molecular assemblages.

To most people in the U.K., indeed throughout Western Europe, space exploration is primarily perceived as 'what NASA does'. This perception is - in many respects - a valid one. Superpower rivalry during the Cold War ramped up U.S. and Soviet space efforts to a scale that Western Europe had no motive to match.

Science is the one culture that's truly global - protons, proteins and Pythagoras's Theorem are the same from China to Peru. It should transcend all barriers of nationality. It should straddle all faiths, too.

Manufacturing doesn't just mean building cars and metal-bashing; it includes making pharmaceuticals and hi-tech electronics. A crucial part of the process is the research and development that allows better and greener products to come to market. Britain has traditionally had a strong science and engineering base.

In our interconnected world, novel technology could empower just one fanatic, or some weirdo with a mindset of those who now design computer viruses, to trigger some kind of disaster. Indeed, catastrophe could arise simply from technical misadventure - error rather than terror.

The practical case for manned spacef light gets ever-weaker with each advance in robots and miniaturisation - indeed, as a scientist or practical man, I see little purpose in sending people into space at all. But as a human being, I'm an enthusiast for manned missions.

Advances in technology - hugely beneficial though they are - render us vulnerable in new ways. For instance, our interconnected world depends on elaborate networks: electric power grids, air traffic control, international finance, just-in-time delivery, and so forth.

Not even the most secular among us can fail to be uplifted by Christianity's architectural legacy - the great cathedrals. These immense and glorious buildings were erected in an era of constricted horizons, both in time and in space.

The scientific community should work as hard as possible to address major issues that affect our everyday lives such as climate change, infectious diseases and counterterrorism; in particular, 'clean energy' research deserves far higher priority. And science and technology are the prime routes to tackling these issues.

Ironically, it is only when disaster strikes that the shuttle makes the headlines. Its routine flights attracted less media interest than unmanned probes to the planets or the images from the Hubble Telescope. The fate of Columbia (like that of Challenger in 1986) reminded us that space is still a hazardous environment.

Darwin and his successors taught us how our biosphere evolved, and thereby transformed our conception of humanity's place in nature. In the twenty-first century, space scientists are setting Darwin in a grander cosmic context - probing the origins of Earth, stars, atoms and the universe itself.

The Blair government perhaps ranks as the best the U.K. has had for 50 years. It cannot match the scale of Attlee's reforms, but has a fine record of constitutional reform and economic competence. In my own areas - science and innovation - there have been well-judged and effective changes.

There's now, for the first time, a huge gulf between the artefacts of our everyday life and what even a single expert, let alone the average child, can comprehend. The gadgets that now pervade young people's lives, iPhones and suchlike, are baffling 'black boxes' - pure magic to most people.

A monkey is unaware that atoms exist. Likewise, our brainpower may not stretch to the deepest aspects of reality. The bedrock nature of space and time, and the structure of our entire universe, may remain 'open frontiers' beyond human grasp.

I hope that by 2050 the entire solar system will have been explored and mapped by flotillas of tiny robotic craft.

It is foolish to claim, as some do, that emigration into space offers a long-term escape from Earth's problems. Nowhere in our solar system offers an environment even as clement as the Antarctic or the top of Everest.

In future, children won't perceive the stars as mere twinkling points of light: they'll learn that each is a 'Sun', orbited by planets fully as interesting as those in our Solar system.

As regards my own 'philosophy,' I continue to be inspired by the music, liturgy and architectural tradition of the Anglican Church in which I was brought up. No one can fail to be uplifted by great cathedrals - such as that at Ely, near my home in Cambridge.

When scientists are asked what they are working on, their response is seldom 'Finding the origin of the universe' or 'Seeking to cure cancer.' Usually, they will claim to be tackling a very specific problem - a small piece of the jigsaw that builds up the big picture.

Some of the 'aha' insights that scientists strive for may have to await the emergence of post-human intellects.