Read the excerpt from Walden. The repose is never complete. The wildest animals do not repose, but seek their prey now; the fox, and skunk, and rabbit, now roam the fields and woods without fear. They are Nature’s watchmen—links which connect the days of animated life. What natural phenomenon is referred to in this excerpt?
the phases of the moon
the food chain
the rotation of the earth
the metamorphosis of animals