KOSMICOS. Most willingly. I have thus far spoken of the hypothesis of evolution as affording an explanation of the origin of distinct animals, regarded simply as living organisms, differentiated from each other by the slow process of development from a common stock, by the operation of certain physical causes. I am now to account to you for the origin of the human mind, upon the same hypothesis, namely, that man is a development from some previous and lower organism. I acknowledge that what we call mind, or intellect, has to be accounted for; and that we who hold the evolution theory of the origin of man as an animal must be able to suggest how his intellect became developed by the operation of the same natural causes which produced his physical organization. It is not material, in this inquiry, whether we agree with Darwin in assuming some one distinct living organism of a very low type, as the original stock from which all the other animal organisms have been derived, or whether we go with Spencer back to the primal molecules of organizable matter, and suppose that from a single cell have been developed all the organisms possessing life, in a regular order of succession. Upon either supposition, the doctrine of evolution explains the origin of the human mind. For, upon either supposition, there was a point in the long series of new forms, each descending from a pre-existing form, at which the manifestations of what we call mind may be said to have begun. This link in the connected chain of organisms occurred where nervous organization began to act with some spontaneous movement, with some power of voluntary exertion, as distinguished from the involuntary exertions of a substance that acted only in a certain and fixed way, although that substance was endowed with life. The substance of nervous organization is alike in all animals. In some it acts in a limited manner, and without volitional control; in others, it acts in more varied modes, and it manifests some power of volitional control and volitional rest, as well as of involuntary movement. But in all animals the substance of which nervous organization is composed--the substance which acts in producing movement, whether voluntary or involuntary--is the same kind of physical structure. In the higher animals, the great nerve-center is the organ called the brain. To this organ proceed the impressions produced upon one set of nerves by external objects, or by light or heat. From the same organ proceed, by another set of nerves, those movements which the animal is endowed with the power of making from within. Contemplating, then, the whole animal kingdom as one great connected family, but divided into different species, all of which have a nervous organization, we find that each species is endowed with the power of generating other individuals of the same species and of the same nervous organization. In the long course of development of the