Let us regard the matter from the objective aspect first, from the side to which the occurrences present themselves as transformations of energy. The state of consciousness being _ex hypothesi_ accompanied or “called into existence” by certain complex and orderly molecular vibrations in the brain or some part thereof, we have to note that from the physical point of view these molecular vibrations constitute an exceeding complex and orderly mode of energy. It is upon this energy that we must fix our attention; the material structure of the brain being what we may call the vehicle of its manifestation. I am anxious that the reader should carefully follow me here. We are too apt to regard the _structure_ as the essential thing on which to concentrate our mental gaze, partly no doubt because, through the invaluable labors of microscopists, we know so much that is definite about this structure. But a more penetrating insight enables us to see that the structure is merely the necessary basis of what is the really important thing—the manifestation of energy. The material structure of a steam-engine is of importance. But why? Because it is the vehicle for the performance of work. That is the really essential part of the business. In like manner nerve-structure is of importance. But why? Because it is the vehicle for what Professor Huxley happily termed the neurosis, the complex and orderly manifestation of energy. The essential importance of looking at the _going_ machine, at the performance of work, at the energy of the matter in motion, not merely the material structure that is moved—the essential importance, I say, of fixing our attention on this, being fairly grasped, we may now proceed to enquire from what the complex and orderly vibrations of the dog’s brain have been evolved. In the fertilised ovum from which the dog was developed, (and the same is true of the amœboid ancestor from which, hypothetically, the race of dogs has been evolved,) there is certainly nothing approaching the orderly complexity of these molecular vibrations. But there are simpler organic modes of motion from which these complex molecular vibrations have arisen by a continuous process of development. It is from these simpler modes of energy in the simpler organic substance of the ovum that the more complex modes of energy which characterise the workings of the dog’s brain have been evolved. In the development of the ovum into the embryo, and thence into the puppy and the dog, we may trace step by step all the stages of the evolution of those material structures which are the vehicles of these special manifestations of organic energy. We may watch the further and further differentiation of the nervous tissue, and the fashioning of the brain and its parts. It is true that we cannot indicate the exact moment when, in the increasing complexity of the tissues, the simpler forms of organic energy pass into the higher form of brain energy accompanied by consciousness. But