It's an anti­gravity metal. Its purpose is to keep you from touching this world of the past in any

way. Stay on the Path. Don't go off it. I repeat. Don't go off." (Bradbury)

Not knowing it, we might kill an important animal, a small bird, a roach, a flower even, thus

destroying an important link in a growing species." (Bradbury)

families of this one particular mouse are destroyed, right?...And all the families of the families of the families of that one mouse! With a stamp of your foot,

you annihilate first one, then a dozen, then a thousand, a million, a billion possible mice!"

survive? For want of ten mice, a fox dies. For want of ten foxes a lion starves. For want of a lion,

all manner of insects, vultures, infinite billions of life forms are thrown into chaos and

destruction. Eventually it all boils down to this: fifty­nine million years later, a caveman, one of a

dozen on the entire world, goes hunting wild boar or saber­toothed tiger for food."

many chess pieces blown in a dry wind ....

But the immediate thing was the sign painted on the office wall, the same sign he had read

earlier today on first entering. Somehow, the sign had changed"