Life would be impossible on such a planet. It wouldn't get enough heat and light, and if it rotated there would be total darkness half of every day. There wouldn't be any native inhabitants. You couldn't expect life - which is fundamentally dependent on light - to develop under such extreme conditions of light deprivation. Half of every axial rotation spent in Darkness! No, nothing could exist under conditions like that.

Even as a youngster, though, I could not bring myself to believe that if knowledge presented danger, the solution was ignorance.

They absorb carbon monoxide and carbon dioxide and give out oxygen. What could be more desirable? And they look good in the bargain. Stop chopping down the rain forests and plant more saplings, and we're on our way.

Many a prophecy, by the mere force of its being believed, is transmuted to fact.

There is no belief, however foolish, that will not gather its faithful adherents who will defend it to the death.

Before another century is done it will be hard for people to imagine a time when humanity was confined to one world, and it will seem to them incredible that there was ever anybody who doubted the value of space and wanted to turn his or her back on the Universe.

Of course there are worlds. Millions of them! Every star you see has worlds, and most of those you don't see.