Herbert Spencer

“ Every desire consists primarily of a mental representation of that which is desired, and secondarily excites a mental representation of the actions by which it is attained; and any such mental representations of the end and the means, imply antecedent experience of the end and antecedent use of the means. To assume that in the course of evolution there from time to time arise new kinds of actions dictated by new desires, is simply to remove the difficulty a step back.
§ 146. Changes of external conditions are named, by Dr. Darwin, as causes of modifications in organisms. ”

“ Not directly, but by successive approximations, do mankind reach correct conclusions; and those who first think in the right direction, loose as may be their reasonings, and wide of the mark as their inferences may be, yield indispensable aid by framing provisional conceptions and giving a bent to inquiry. ”

“ Already it has been necessary to speak of the causes of organic evolution in general terms; and now we are prepared for considering them specifically. The task before us is to affiliate the leading facts of organic evolution, on those same first principles conformed to by evolution at large. ”

“ One of the earliest who in modern times (1735) contended that organisms are indefinitely modifiable, and that through their modifications they have become adapted to various modes of existence, was De Maillet. But though De Maillet supposed all living beings to have arisen by a natural, continuous process, he does not appear to have had any definite idea of that which determines this process. In 1794, in his Zoonomia, Dr. Erasmus Darwin gave reasons (sundry of them valid ones) for believing that organized beings of every kind, have descended from one, or a few, primordial germs ”

“ He asserts that "dans sa marche, la nature a commencé, et recommence encore tous les jours, par former les corps organisés les plus simples;" and that "les premières ébauches de l'animal et du végétal étant formées dans les lieux et les circonstances convenables, les facultés d'une vie commençante et d'un mouvement organique établi, ont nécessairement développé peu à peu les organes, et qu'avec le temps elles les ont diversifies ainsi que les parties." ”

“ Darwin ascribes to animals, he says they have a capacity for being modified by processes which their own desires initiate. He speaks of powers as "excited into action by the necessities of the creatures which possess them, and on which their existence depends;" ”

“ His wild notions about the way in which natural causes acted in the production of plants and animals, must not make us forget the merit of his intuition that animals and plants were produced by natural causes. ”

“ Darwin's brief exposition, the belief in a progressive genesis of organisms is joined with an interpretation having considerable definiteness and coherence. In the space of ten pages he not only indicates several of the leading classes of facts which support the hypothesis of development, but he does something towards suggesting the process of development. ”

“ After enumerating various appliances for procuring food, he says they all "seem to have been gradually produced during many generations by the perpetual endeavour of the creatures to supply the want of food, and to have been delivered to their posterity with constant improvement of them for the purposes required." ”

“ One of the anticipations was this ascription of development to some inherent tendency. To the "plan général de la nature, et sa marche uniforme dans ses opérations," Lamarck attributes "la progression évidente qui existe dans la composition de l'organisation des animaux;" and "la gradation régulière qu'ils devroient offrir dans la composition de leur organisation," he thinks is rendered irregular by secondary causes. Essentially the same in kind, though somewhat different in form, is the conception put forth in the Vestiges of Creation ”

“ These, and sundry other passages, joined with his general scheme of classification, make it clear that Lamarck conceived adaptive modification to be, not the cause of progression, but the cause of irregularities in progression. The inherent tendency which organisms have to develop into more perfect forms, would, according to him, result in a uniform series of forms ”

“ Contrasted with the dogmas of his age, the idea of De Maillet was a great advance. Before it can be ascertained how organized beings have been gradually evolved, there must be reached the conviction that they have been gradually evolved ”

“ He suggests the possibility "that all warm-blooded animals have arisen from one living filament, which The Great First Cause endued with animality, with the power of acquiring new parts, attended with new propensities, directed by irritations, sensations, volitions, and associations ”