While some Greek philosophers had theories about the gradual evolution of life, Plato (427–347B.C.E.) and Aristotle (384–322B.C.E.) were not among them. In the 1700s, “natural theology” (the explanation of life as the manifestation of the creator’s plan) held sway in Europe. This idea was the motive force behind the work of Carl Linnaeus (1707–1778), who was the first to classify all known living things by kingdom. Also popular prior to the work of Charles Darwin (1809–1882) were the theories of “special creation” (creationism), “blending inheritance” (that offspring were always the mixture of the traits of their two parents), and “acquired characteristics.”