in Thoreau’s Journal:

1850

I feel a little alarmed when it happens that I have walked a mile into the woods bodily, without getting there in spirit…This afternoon, late and cold as it is, has been a sort of Indian summer. Indeed, I think we have summer days from time to time the winter through, and that it is often the snow on the ground which makes the whole difference.

This afternoon the air was indescribably clear and exhilarating, and though the thermometer would have shown it to be cold, I thought there was a finer and purer warmth than in summer, a wholesome, intellectual warmth in which the body was warmed by the mind’s contentment, —the warmth hardly sensuous, but rather the satisfaction of existence.

1860

I remember perhaps that 15 years ago there was not a single tree in this pasture– not a germinating seed—of one—& now it is a pretty dense forest 10 feet high— I confess that I love to be convinced of this inextinguishable vitality in Nature. I would rather that my body should be buried in a soil thus wide-awake—than in a mere inert & dead earth.