Each star system is an island in space， quarantined from its neighbors by the light-years. I can imagine creatures evolving into glimmerings ofknowledge on innumerable worlds， every one of them assuming at first their puny planet and paltry few suns to be all that is. We grow up in isolation. Only slowly do we teach ourselves the Cosmos.
Some stars may be surrounded by millions of lifeless and rocky worldlets， planetary systems frozen at some early stage in their evolution. Perhaps many stars have planetary systems rather like our own； at the periphery， great gaseous ringed planets and icy moons， and nearer to the center， small， warm， blue-white， cloud-covered worlds. On some， intelligent life may have evolved， reworking the planetary surface in some massive engineering enterprise. These are our brothers and sisters in the Cosmos. Are they very different from us？ What is their form， biochemistry， neurobiology， history， politics， science， technology， art， music， religion， philosophy？ Perhaps some day we will know them.
We have now reached our own backyard， a light-year from Earth. Surrounding our Sun is a spherical swarm of giant snow-balls composed of ice and rock and organic molecules： the cometary nuclei. Every now and then a passing star gives a tiny gravitational tug， and one of them obligingly careens into the inner solar system. There the Sun heats it， the ice is vaporized， and a lovely cometary tail develops.
We approach the planets of our system， largish worlds， captives of the Sun， gravitationally constrained to follow nearly circular orbits， heated mainly by sunlight.Pluto， covered with methane ice and accompanied by its solitary giant moon Charon， is illuminated by a distant Sun， which appcars as no more than a bright point of light in a pitchblack sky. The giant gas worlds， Neptune， Uranus， Saturn—the jewel of the solar system—and Jupiter all have an entourage of icy moons. Interior to the region of gassy planets and orbiting icebergs are the warm， rocky provinces of the inner solar system. There is， for example， the red planet Mars， with soaring volcanoes， great rift valleys， enormous planet-wide sandstorms， and， just possibly， some simple forms of life. All the planets orbit the Sun， the nearest star， an inferno of hydrogen and helium gas engaged in thermonuclear reactions， flooding the solar system with light.
Finally， at the end of all our wanderings， we return to our tiny， fragile， blue-white world， lost in a cosmic ocean vast beyond our most courageous imaginings. It is a world among an immensity of others. It may be significant only for us. The Earth is our home， our parent. Our kind of life arose and evolved here. The human species is coming of age here. It is on this world that we developed our passion for exploring the Cosmos， and it is here that we are， in some pain and with no guarantees， working out our destiny.
Welcome to the planet Earth—a place of blue nitrogen skies， oceans of liquid water， cool forests and soft meadows， a world positively rippling with life. In the cosmic perspective it is， as I have said， poignantly beautiful and rare； but it is also， for the moment， unique. In all our journeying through space and time， it is， so far， the only world on which we know with certainty that the matter of the Cosmos has become alive and aware. There must be many such worlds scattered through space， but our search for them begins here， with the accumulated wisdom of the men and women of our species， garnered at great cost over a million years. We are privileged to live among brilliant and passionately inquisitive people， and in a time when the search for knowledge is generally prized. Human beings， born ultimately of the stars and now for a while inhabiting a world called Earth， have begun their long voyage home.
14
Rural Life in England
英国乡村
“Oh！ friendly to the best pursuits of man， Friendly to thought， to virtue， and to peace， Domestic life in rural pleasure passed！”
Cowper.
The stranger who would form a correct opinion of the English character，must not confine his observations to the metropolis. He must go forth into the country； he must sojourn in villages and hamlets： he must visit castles， villas， farm-houses， cottages； he must wander through parks and gardens； along hedges and green lanes： he must loiter about country churches； attend wakes and fairs， and other rural festivals； and cope with the people in all their conditions， and all their habits and humours.
In some countries， the large cities absorb the wealth and fashion of the nation； they are the only fixed abodes of elegant and intelligent society， and the country is inhabited almost entirely by boorish peasantry. In England， on the contrary， the metropolis is a mere gathering place， or general rendezvous， of the polite classes， where they devote a small portion of the year to a hurry of gaiety and dissipation， and having indulged this carnival， return again to the apparently more congenial habits of rural life. The various orders of society are therefore diffused over the whole surface of the kingdom， and the most retired neighbourhoods afford specimens of the different ranks.