From Autumn Transition

I am alarmed when it happens that I have walked a mile into the woods bodily, without getting there in spirit. In my afternoon walk I would fain forget all my morning occupations and my obligations to Society. But it sometimes happens that I cannot easily shake off the village. The thought of some work will run in my head and I am not where my body is — I am out of my senses. In my walks I would fain return to my senses. What business have I in the woods, if I am thinking of something out of the woods?

Thoreau