12/29/56, Journal, IX 200. We must go out and re-ally ourselves to Nature every day. We must make root, send out some little fibre at least, even every winter day. I am sensible that I am imbibing health when I open my mouth to the wind. Staying in the house breeds a sort of insanity always. Every house is in this sense a hospital.
Bonus: Thoreau’s “Excursions” is available for free on Project Gutenberg.