Walden is an account of the time Thoreau lived alone in a cabin in Concord, Massachusetts. He built the cabin, grew and sold vegetables, and contemplated consciousness and identity. The theme is simple - it focuses on living in natural surroundings, and in essence, the work may be seen as a declaration of independence, a social experiment, quest of spiritual discovery, and a self-reliance guide. The text contains scientific observations of nature along with metaphorical and poetic applications of natural phenomena. Thoreau identifies many plants and animals by their popular and scientific names, records the color and clarity of various bodies of water, dates and describes the freezing and thawing of the pond, and describes his experiments to measure the shape and depth of the pond.