Read the excerpt from walden. time is but the stream i go a-fishing in. i drink at it; but while i drink i see the sandy bottom and detect how shallow it is. its thin current slides away, but eternity remains. in the excerpt, thoreau mostly uses imagery to illustrate

a. the beauty that is in the natural world.

b. the idea that he is unconcerned with dying.

c. his argument that everyone should move more slowly.

d. his belief that the passing of hours and days is irrelevant.