I'm only a four-dimensional creature. Haven't got a clue how to visualise infinity. Even Einstein hadn't. I know because I asked him

My parents were not scientists. They knew almost nothing about science. But in introducing me simultaneously to skepticism and to wonder, they taught me the two uneasily cohabiting modes of thought that are central to the scientific method.

And you are made of a hundred trillion cells. We are, each of us, a multitude.

Before we invented civilization our ancestors lived mainly in the open out under the sky. Before we devised artificial lights and atmospheric pollution and modern forms of nocturnal entertainment we watched the stars. There were practical calendar reasons of course but there was more to it than that. Even today the most jaded city dweller can be unexpectedly moved upon encountering a clear night sky studded with thousands of twinkling stars. When it happens to me after all these years it still takes my breath away.

The total number of stars in the Universe is larger than all the grains of sand on all the beaches of the planet Earth.

Exploration is in our nature. We began as wanderers, and we are wanderers still. We have lingered long enough on the shores of the cosmic ocean. We are ready at last to set sail for the stars.

If you look at Earth from space you see a dot, that's here. That's home. That's us. It underscores the responsibility to deal more kindly and compassionately with one another and to preserve and cherish that pale blue dot, the only home we've ever known.