The writing of Henry David Thoreau is as full of life today as it was when he published Walden one hundred years ago. In seeking to understand nature, Thoreau sought to "lead a fresh, simple life with God." In 1848 a seeker named Harrison Blake, yearning for a spiritual life of his own, asked the then-fledgling writer for guidance. The fifty letters that ensued, collected here for the first time in their own volume by Thoreau specialist Bradley P. Dean, are by turns earnest, oracular, witty, playful, practical and deeply insightful and inspiring, as one would expect from America's best prose...