 During most of his own life conservationism was not yet on the political agenda, and Tolkien himself did not directly express conservationist views—except in some private letters, in which he tells about his fondness for forests and sadness at tree-felling.In later years, a number of authors of biographies or literary analyses of Tolkien conclude that during his writing of "The Lord of the Rings", Tolkien gained increased interest in the value of wild and untamed nature, and in protecting what wild nature was left in the industrialized world.Tolkien devised several themes that were reused in successive drafts of his "legendarium", beginning with "The Book of Lost Tales", written while recuperating from illnesses contracted during The Battle of the Somme.