Based on a trip with his brother in 1839, «A Week on the Concord and Merrimack Rivers» is an excellent example of Thoreau's talent for naturalistic writing. In exquisite detail Thoreau depicts the nature that surrounds him over the course of his trip. One of only two books to be published during his lifetime, Thoreau began work on «A Week on the Concord and Merrimack Rivers» following his brother's death in 1842, however the work was not fully completed and published until 1849. A failure when first published «A Week on the Concord and Merrimack Rivers» has since been recognized as one of Thoreau's great naturalist works.