Answer:
He characterizes nature by its constant alertness and activity.
Step-by-step explanation:
Thoreau`s description of nature is characterized by contrast. He is calm, enjoys a walk by the lake, nothing upsets him, but the vice versa, he is breathing with the nature around him and follows its steps. On the other hand, nature, as always is alive, wind, clouds, waves, animals, everything is moving, living untouched by random visitors like Thoreau. So from the lively surroundings and eternally active spirit of nature, he extracts the feeling of peace.