Essays on the Vedas. He was strongly influenced by Vedanta, and much of his writing has strong shades of nondualism. One of the clearest examples of this can be found in his essay "The Over-soul": The central message Emerson drew from his Asian studies was that "the purpose of life was spiritual transformation and direct experience of divine power, here and now on earth." In 1847–48, he toured the British Isles. He also visited Paris between the French Revolution of 1848 and the bloody June Days. When he arrived, he saw the stumps of trees that had been cut down to form barricades in the February riots. On May 21, he stood on the Champ de Mars in the midst of mass celebrations for concord, peace and labor. He wrote in his journal, "At the end of the year we shall take account, & see if the Revolution was worth the trees." The trip left an important imprint on Emerson's later work. His 1856 book English Traits is based largely on observations recorded in his travel journals and notebooks. Emerson later came to see the American Civil War as a "revolution" that shared common ground with the European revolutions of 1848. In a speech in Concord, Massachusetts on May 3, 1851, Emerson denounced the Fugitive Slave Act: That summer, he wrote in his diary: In February 1852 Emerson and James Freeman Clarke and William Henry Channing edited an edition of the works and letters of Margaret Fuller, who had died in 1850. Within a week of her death, her New York editor, Horace Greeley, suggested to Emerson that a biography of Fuller, to be called Margaret and Her Friends, be prepared quickly "before the interest excited by her sad decease has passed away". Published under the title The Memoirs of Margaret Fuller Ossoli, Fuller's words were heavily censored or rewritten. The three editors were not concerned about accuracy; they believed public interest in Fuller was temporary and that she would not survive as a historical figure. Even so, it was the best-selling biography of the decade and went through thirteen editions before the end of the century. Walt Whitman published the innovative poetry collection Leaves of Grass in 1855 and sent a copy to Emerson for his opinion. Emerson responded positively, sending Whitman a flattering five-page letter in response. Emerson's approval helped the first edition of Leaves of Grass stir