Page:The succession of forest trees, and Wild apples.djvu/6

they followed the Concord River to where it enters the Merrimac, then went up that river to its source, and finally back to the starting-place at Concord. ln 1845 he built a hut in the woods by Walden Pond, where he lived for two years, watching the life in woods and pond and air. Walden, published in 1854, is his most famous book, and contains the record of his experience as a hermit. These two books were the only ones by Thoreau published in his lifetime, but he contributed occasionally to periodicals, and he kept full journals. After his death his printed papers were gathered, and his journals drawn from to make Excursions in Field and Forest, The Maine Woods, Cape Cod, Letters to Various Persons, A Yankee in Canada, Early Spring in Massachusetts, and Summer. The two papers which follow, as well as Emerson s sketch, are from the volume of Excursions.