2. At present, every individual animal or plant commences its existence as an organism of extremely simple anatomical structure; and it acquires all the complexity it ultimately possesses by gradual {41} differentiation into parts of various structure and function. When a series of specific forms of the same type, extending over a long period of past time, is examined, the relation between the earlier and the later forms is analogous to that between earlier and later stages of individual development. Therefore, it is a probable conclusion that, if we could follow living beings back to their earliest states, we should find them to present forms similar to those of the individual germ, or, what comes to the same thing, of those lowest known organisms which stand upon the boundary line between plants and animals. At present, our knowledge of the ancient living world stops very far short of this point. 3. It is generally agreed, and there is certainly no evidence to the contrary, that all plants are devoid of consciousness; that they neither feel, desire, nor think. It is conceivable that the evolution of the primordial living substance should have taken place only along the plant line. In that case, the result might have been a wealth of vegetable life, as great, perhaps as varied, as at present, though certainly widely different from the present flora, in the evolution of which animals have played so great a part. But the living world thus constituted would be simply an admirable piece of unconscious machinery, the working out of which lay potentially in its primitive composition; pleasure and pain would have no place in it; it would be a veritable Garden of Eden without any tree of the knowledge of good and evil. The question of the moral government of such a world {42} could no more be asked, than we could reasonably seek for a moral purpose in a kaleidoscope.