Of course all the unceasing work of the brain tends to wear it out, and does wear it out; but this wearing out is not the result of any one part of its unceasing work. The thinking part of its work, indeed, does not seem to be specially wearing out in its effects. The maintenance of respiration and of the circulation of the blood are also wearing out, and perhaps more actively.

(11) If thinking of some sort goes on all through life, then, as John Reid says, it may be 'so essentia to life, that, if the association is broken, death must inevitably ensue' - as inevitably as when breathing ceases or the circulation of the blood.

It so happens that there is a Death from which there may, or may not, be a coming back to Life, refer to syncope, which is entirely different from sleep of any kind or any degree. It also differs radically from the deepest coma or the deepest drug narcosis. During all such states delirious thinking goe3 faintly on. But there is no delirious thinking - no dream-thinking - no thinking of any kind in syncope. Thinking of all sorts then ceases. It is a true state of suspended animation. Indeed it is actual death while it lasts, and it often lasts for ever. If recovery takes place, both life and thinking come back together, so that there is no contradiction within the view I take.

The point is that thinking is essential to the continuance of life. It need not be the kind of think-ing which is under direction of the will, but thinking of some sort must go on if life is to continue. When all thinking ends, life ends. We cannot think unless we are alive, and we cannot be alive without thinking. All this seems to be true, and no difficulty arises out of the inability to define with precision what living and thinking are.

In the work of the Psychological Research Society, this coming back from Death to Life, as happens in the restoration from syncope, has not received the attention it deserves.

(12) It is beyond question that thinking goes on in Some parts of sleep, and in those parts consciousness is as certainly not lost. Consciousness, indeed, is coextensive with all mental operations, and, if so, it must exist in dream-thinking - both in that which is remembered and in that which is forgotten.

There appear to be infinite qualities and gradations of consciousness, but the word, as ordinarily used, denotes the higher qualities and gradations. It is mere phrasing and explains nothing, to speak of the more obscure mental processes, those, for instance, which are under the influence of habit, say in the playing of music, as sub-conscious. In like manner it is nothing but phrasing to talk of 'a half-consciousness existing in dreams.' So long as there are mental operations of any kind, consciousness in some degree exists, and this covers everything. We can speak properly enough of the conscious mind, but we cannot speak of the unconscious mind. Consciousness does not exist apart from mind.

The term is not susceptible of definition, but it is used with exceeding looseness and with meanings which differ greatly. Most subtle and ingenious differentiations enter into the various clothings of its meaning, but, so far as I am able to discover, these are not understanded of the people, at least of those of them among whom I have my being.

(13) It seems desirable that I should say here that I recognise the danger arising from the use of undefined, or rather, perhaps, undefinable words, but I feel obliged, or at least it suits me, to use words of this character. I cannot, for instance, tell what is meant by Will, but I assume its existence and use the word. Nor do I know of any satisfying definition of the words Thinking, Sleeping, Dreaming, or Remembering. But I shall use these and other such words as naming things which, in the general opinion, have an existence, and I do not think that my doing this will cause any misunderstanding of the special views I express in regard to dreaming.

(14) While we are using the thinking part of the brain's work in a state of wakefulness, we bring it under the control and direction of the Will, In other words, we do not allow it to go on without guidance. We direct it into certain channels and keep it there. We exercise an inhibiting power over it.

The Will does its controlling work in regard to thinking more easily in some directions or conditions than in others. In adults, for instance, it can more readily insist on the mind's giving attention to certain things, than it can insist on the withdrawal of attention from things to which it has been given, especially if these things involve the emotions rather than the intellect, even though the attention first given to them was under the direct guidance of the Will. Otherwise stated, it can, in the case of an adult, more easily keep thinking employed on the solution of a problem in mathematics or on the writing of an essay, than it can withdraw it from employment in considering a bereavement by death or the loss of a fortune. This relates to adults. Nearly the opposite holds good in regard to children. In their case, the Will has difficulty in keeping the mind engaged in purely intellectual work, but finds it easy to withdraw it from dwelling on a sorrow or a disappointment. The child wills to weep and grieve over a broken toy, but the arrival of a playmate or the gift of a new toy makes it immediately will to be happy and to cease weeping. Hence it happens that worry usually attends the work which does harm to the adult brain, while the brain of the child is little liable to injury from worry, but can be easily hurt by excessive and forced intellectual work.

(15) It has often been pointed out that there is nothing more laborious than the sustained exertion of Will, whether it be employed in things so different as attending to a subject of study or directing our limbs in unwonted action. In forcing attention the Will becomes fatigued, and it is the Will which comes to need rest and which gets it in sleep. In the Thinking which goes on in the state of sleep there is an absence of the sense of weariness. It is not then under control or direction. It seems, if I may so write of it, to be left free to sport, and through this free unrestrained play, as well as through the Will's rest from work, refreshment appears to come to what we call Thinking, the weariness of which may be regarded as arising out of a forced subjection to the directing power of the Will. Dreaming has been spoken of as a mental recreation - the mind being regarded as disporting itself. It is the directing power, which chiefly demands rest through a cessation of work, and it finds it during sleep.