Book excerpt: Most people who care about nature cannot help but use religious language to describe their experience. We can trace many of these conceptions of nature and holiness directly to influential nineteenth-century writers, especially Henry David Thoreau (1817-1862). In Walden, he writes that "God himself culminates in the present moment," and that in nature we encounter, "the workman whose work we are." But what were the sources of his religious convictions about the meaning of nature in human life?