In a subsequent section of the same chapter, Locke asserts that most men pass a great part of their lives without dreaming, and that he once knew a scholar who had no bad memory, who told him he had never dreamed in his life till after the occurrence of a fever in the twenty-fifth or twenty-sixth year of his age. Examples of persons who have not ordinarily dreamed are adduced by the ancient writers. Pliny[67] refers to men who never dreamed. Plutarch[68] alludes to the case of Cleon, who, in living to an advanced age, had yet never dreamed; and Suetonius[69] declares that before the murder of his mother he had never dreamed. A lady who was under my care for a serious nervous affection declared to me that she never had had but one dream in her life, and that was after receiving a severe fall in which she struck her head. And yet, notwithstanding the experience of every one that sleep often happens without the accompaniment of dreams, the great majority of writers hold the view that the brain is never at rest. Doubtless this opinion has its origin partly in the doctrine that the mind is a something altogether independent of and superior to the brain. They appear to be incapable of appreciating the fact that when the brain is in a state of complete repose there can be no mental manifestation, and that all intellectual phenomena are the results of cerebral activity. Another cause for their belief is the fact that they make no distinction between dreaming and thinking, whereas it is very evident that the two are not to be placed in the same category. Thinking is an _action_ which requires cerebral effort, and which is undertaken with a determinate purpose. We will to think, and we think what we please; but it is very different with our dreams, which come and go without any power on our part to regulate or direct them. To think requires all the faculties of the mind; to dream necessitates only the memory and the imagination. In thinking, the brain is active in all its parts; in dreaming, it is nearly entirely quiescent. Writers who contend for the doctrine of constant mental activity regard the brain as the organ or tool of the mind, a structure which the mind makes use of in order to manifest itself. Such a theory is certain to lead them into difficulties, and is contrary to all the teaching of physiology. The full discussion of this question would be out of place here; I will, therefore, only state that this work is written from the stand-point of regarding the mind as nothing more than the result of cerebral action. Just as a good liver secretes good bile, a good candle gives good light, and good coal a good fire, so does a good brain give a good mind. When the brain is quiescent there is no mind.