These two works chart Lamarck's evolutionary theory of species development. Lamarck was the first zoological writer to use the term "invertebrates" instead of catergorising them as "insects and worms," holding the belief that the historical development of the higher forms of life was a continous process of specialization. His work was originally dismissed by Darwin, partly because of his badly presented arguments, but Darwin, in the preface to the third edition of the Origin of Species, paid him this tribute: "He first did the eminent service of arousing attention to the probability of all change in the organic as well as in the inorganic world being the result of law, and not of miraculous interposition."