The Germans have invented a special name for the phantoms of the "doze-world," the hallucinations hypnagogiques of Maury, namely, the Schlummerbilder, generally visual images occasioned, as it is presumed, by sensations aroused, in the absence of external causes, by some physical commotion of the nerves themselves. Yet in spite of some learned argument in favour of these images being the stuff of which dreams are commonly composed, it is exceedingly doubtful whether more than a small minority (among whom, by-the-bye, is to be reckoned the notable instance of Goethe) are aware of these images at all. With most of us it would seem more probable that association of ideas is sufficient to account for the raw material of most of our dreaming.

There is one very curious thing about the way in which our ideas during sleep are associated with the ideas that were in our minds shortly before we went to sleep. It is the common experience of "every schoolboy," as Lord Macaulay said, that the "rep."-lines to be learned by heart for repetition in the morning school - if conned over only carelessly over night will often be found clear in his mind in the morning. This would not be so curious if we could find any indication that the boy s mind was occupied with these lines during his sleep. But in every case - that has come my way at least - the boy has declared that he did not dream of "such rot as 'rep.,'" as he is likely to call it, at all. Of cricket or football he may have dreamt, but certainly not of the 'rep.' And yet it assuredly looks as if his mind must have been busy, unknown to himself, with that unsavoury subject during sleep; or else how can he come to know it so much better? There is here an unexplained mystery, as it seems to me; nor can I find that any of the scientific books throw any real light on it. It is a common observation about dreams how absolutely their cause is beyond our control.

We cannot determine what they shall be about, by fixing our mind on any particular subject before we drop off to sleep, nor can we, after waking out of a pleasant dream, prolong it, by thinking of its incidents, when we again fall asleep. I am well aware that there are exceptions to this rule - people who claim, and no doubt justly, to be able to influence in a great measure the course of their dreaming thoughts, but they are in a very small minority. The rule, most certainly, is as I have stated. We cannot, by taking thought as we go to sleep, exercise any control over the course of our subsequent dreams. So true is this, that among the many who have written to me there are two who say that if they specially wish to avoid dreaming of a certain subject that they think likely to engage their minds during sleep, they deliberately concentrate their thoughts on this subject as they lay their heads on the pillow, with the certainty that this would prevent its occurrence in their dreams - a very remarkable statement indeed, as it seems to me, in view of the well-known facts about the schoolboys' "rep.," etc., which seem to argue so strongly in the opposite sense.

It would almost seem to suggest the inference that two distinct mental operations go on while in sleep-that there is one set of ideas of which we think, unconsciously, and another set of which we consciously dream; and further, that while we are likely to think of the ideas on which our attention was set shortly before going to sleep, we are not, on the whole, at all likely to dream of them. On the other hand we are very apt in dreams to recur to all those ideas and impressions with which our minds are habitually occupied, though not those to which we have given a recent and forced attention; just as the schoolboy, though he has lately concentrated himself on his "rep.," more often dreams of the cricket and football which are the more natural and habitual occupation of his mind.

Attention and study, as we have said, weaken as we drop off to sleep. It is very common with most of us, I think, as we lay our heads on the pillow, to say to ourselves, more or less consciously, "now here I am, going to sleep at the end of another day; let's see what I have done in it." And a mental review of the day's work begins - and commonly ends, as.

the attention weakens - with the contemplation of the incident in it that has interested us most, and this in spite of all our intention to keep our minds concentrated on a particular object. We may conjecture that the explanation of the exceptional cases noticed above (of a man dreaming of the subject that he has suggested to his mind as he laid himself down to sleep) may be that this subject happens to be the one with which his mind has been most occupied during the day, the most remarkable incident of his day. Of course this theory is rather contradicted by the experience of those who insure avoidance in their dreams of a certain subject by fixing their minds on it as they lie down, but perhaps, again, their experience is too exceptional to be regarded as any valid argument on the general question.

The schoolboy does not dream of his "rep." It is to be noted that when a man's mind has been so engrossed in his work that it becomes the subject matter of his dreams, his sleep is seldom refreshing and his state is morbid. This is to be explained on the physical side by saying that the apparatus employed in his daily work does not get its natural rest, does not sleep in fact, and get the chemical constitution of its fibres and cells repaired.

There is not the least doubt that when we begin to investigate this whole matter of dreaming, matter that we are obliged to investigate mostly by noting our own symptoms, we have to be particularly on our guard against self-deception. It is so easy to imagine that we have visual hallucinations, or whatever we please to term them, so easy even to encourage ourselves by unconscious self-suggestion to have them. At every stage we have to regard ourselves with the greatest suspicion, as not only possible, but very probable, frauds, for the purpose of such an inquiry. And this being so, it is permissible that we should mete out at least equal measure of this critical suspicion to the account of their symptoms that others give us. It is very difficult for us to avoid becoming slightly neurotic when our attention is continuously fixed on our own nerves (which are apparatus that we never ought to think about at all) and we are aroused to more than a suspicion of neurotic tendency in Maury, who has given us perhaps the most complete survey of the whole question, by some of his state* ments of his own symptoms, both in the sleeping and the waking state.