Refreshment of course also comes to the Will from the repose, during steep, of the muscles, which it has so constantly to call into action in those who are awake.

Darwin says that it is the 'part of sleep to suspend volition.' It is perhaps not quite safe to go further, and say that the sole necessitating cause of sleep, and the only cause of fatigue, is the exercise of volition. The attitude of the cataleptic, not being voluntary, seems to cause no fatigue. What the cataleptic does could not be voluntarily done. So the ravings of delirium are not directed by the will, and fatigue does not seem to follow. Dream-thinking is involuntary, and does not tire us. So is it also with breathing and the beating of the heart.

If the mind were kept incessantly at work for a long time in a quite orderly manner, that is, kept constantly at work by the power of the will in a particular channel or directed to a particular subject, injury would almost certainly follow. Fortunately, in normal conditions, no such protracted and complete inhibition is possible in the case of adults. After a time the mind refuses to obey the will and breaks off into sport; or rather, to put it more correctly, the will gets wearied, gives up inhibiting, and permits thinking to play without any control, during which play there is a manifestation of what may be called mental disorder, and so the injury is averted. I have elsewhere shown that children and adults are not in line in this matter, as regards both the intellectual and emotional workings of the mind.

(16) It is necessary to bear in mind that there are different degrees of Sleep. This is evidenced in the familiar phrases - deep sleep, light sleep, broken sleep, half-awake, wide-awake. It would be easy to multiply phrases of a like kind which are in common use. The constant employment of such phrases points to a thing of importance. It is this. There is certainly an imperfect sleep and an imperfect waking. There is, indeed, every possible variation from complete wakefulness to profound sleep. The gradation of states which connects the waking and sleeping life of man has been called infinite, and not without reason.

I do not think that it can be held by any one that thinking ceases during states of half-sleep, though such thinking as then goes on is of little B value, being only partially directed and but loosely kept to its subject.

(17) It has been alleged that during sleep valuable legal opinions have been written, difficult mathematical problems solved, and poetry and music of a high character composed. All such things I believe to be fables. Belief in them, indeed, has never been asked except upon slender evidence, which under examination falls to pieces. In dreams there is no coherent thinking, directed to a particular end and kept there. Spurzheim goes the great length of saying that 'persons sometimes reason better asleep than awake,' but of this there is no evidence of any kind, even as applicable to persons whose reasoning when awake can scarcely be said to have value. As regards persons of high intellectual power, I think that it may properly be called nonsense.

In like manner, though walking in sleep seems to be a well-established possibility, the stories of the wonderful and all but impossible balancings of sleepwalkers on roofs of houses and narrow ledges may be accepted as the outcome of a prevalent desire to mauufacture the marvellous. Not one of such stories seems to me to be well-established, even admitting that the sleep-walker may not have been in deep sleep.

The somnambulist is said to 'walk on perilous ridges with steady feet,' and to perform feats of a character which he would be quite unable to perform if he were awake, and which no other person, who was awake, could perform. Such statements are freely made and fully believed, but I have not succeeded in finding any competent observer who could say that with his own eyes under proper conditions he had witnessed the performance of these marvellous feats. I have not had very many opportunities of sifting statements of this nature, but such as have fallen in my way have invariably led to the unhesitating conclusion that they were in a strong sense inaccuratc. The temptation to magnify in such matters is wide and deep. Common sense and common experience should lead to the expectation that magnifying will take place in the narratives of their occurrence, and, therefore, to a refusal to accept them as true if they are not convincingly supported. Nothing, so far as I am aware, is known to justify the belief that in sleepwalking 'resources are brought into play which are beyond ordinary reach.'

(18) It is difficult to say how far a drowsy person is from what is called sleep. He may be very near it. He is practically asleep if he is exercising no control over his thinking, and the less the control he exercises the nearer he is to sleep. So it is also with the man who is in what we call a reverie or brown study -' apparent thought, but real vacuity,' - or whose mind, in popular phrase, is wandering. He may be looked on as in a state intermediate between sleep and waking-in what has been called a slumberous state. Going further, it can scarcely be questioned that there are persons who are properly enough described as rarely wide-awake, and whose ordinary thinking approaches in character to what I have called dream-thinking. In this state of halfsleep, if I may so call it, it is quite certain that thinking never ceases. It is only a little less certain in a state of deep sleep.

(19) It has also to be remembered that states of full sleep may be, and often are, of extremely short duration - so short as to be accurately enough called momentary. Slumbering moments are not a fancy. Droppings into these short sleeps may occur with great abruptness, and the restored wakefulness may come as abruptly. Indeed a person may scarcely he aware that sleep has occurred. There may be a frequently repeated, as well as a rapid, passing from a state of wakefulness into sleep and out of it again. It has been actually observed to occur three times in a minute, but there is no reason for thinking that it may not occur more frequently. The most remarkable short sleep on record is one in which the sleeper had what he regarded as 'a long dream carrying him through many scenes and events,' and which occupied fifteen seconds - the measurement of the time being apparently satisfactory.