Showing the influence of a uniquely American form of mysticism known as Transcendentalism, which eschewed the general society and culture of the time, the writing is distinguished by an explosively innovative free verse style and previously unmentionable subject matter. Exalting nature, celebrating the human body, and praising the senses and sexual love, the monumental work was condemned as "immoral." Whitman continued evolving Leaves of Grass despite the controversy, growing his influential work decades after its first appearance by adding new poems with each new printing.