 These intervening inquiries, conducted between 1844 and 1856, positioned Darwin to deal with the question of species permanence against an extensive empirical background. The initial major synthesis of these investigations takes place in his long manuscript, or “Big Species Book”, commenced in 1856, known in current scholarship as the “Natural Selection” manuscript. This formed the immediate background text behind the published Origin. Although incomplete, “Natural Selection” provides insights into many critical issues in Darwin’s thinking. It was also prepared with an eye to the scholarly community. This distinguishes its form of argument from that of the subsequent “abstract” which became the published Origin of Species. “Natural Selection” contained tables of data, references to scholarly literature, and other apparatus expected of a non-popular work, none of which survived in the published Origin.