There are conditions, such as fatigue or sleep, in which the effort necessary to examine the truth of a proposition seems too great, and suggestions are accepted which would be rejected in a state of fuller consciousness. For example, I was awakened one night, when a hospital resident, and told that one of my patients was very restless. I could not remember the man, but asked a few questions about him and ordered a soporific. Next morning on waking I became aware that I had no such patient, and on enquiry found that I had been mistaken for another resident whose slumbers had been undisturbed, thanks to my suggestibility, for had I been fully awake I should have repudiated any connection with the case. The confident manner of the messenger assisted the suggestion, and I like to think that had there been a trick intentionally played upon me even my sleepy consciousness might have detected some warning change of tone. Psychologists regard hypnotic suggestibility as only a further stage of this sleepy non-resistance, but I see in the former a more active desire to accept. Though suggestion might be further classified according to the factors concerned in its acceptance, the class showing 'receptivity' is the important one for our consideration. There remains auto-suggestion to be considered; it is as difficult to define as suggestion, but in the absence of any more precise term it must be accepted as indicating certain mental processes. The sensations felt in the arms and hands by the water-diviner or table-turner are partly the result of auto-suggestion and partly of muscular contractions, themselves produced by the same cause, and some of the varied sensations of the hysteric are of similar origin. Creepy feelings at the mention of snakes, and unpleasant sensations at the thought of those 'minor horrors of war' that live in undergarments, are further examples. As far as the persons concerned are able to judge, the sensations are often real enough, though it was long before I could believe that a confirmed hysteric who complained of a severe pain really suffered from that pain; the description of a water-diviner's sensations, given by himself and quoted in another chapter, are such that one must believe in the honesty of the writer. One might say auto-suggestion arises from the unconscious or from a dissociated stream of consciousness, and this would make it account for hallucinations and obsessions, but here we must again take account of borderline cases. The person who feels a cold shiver at the mention of a snake cannot tell us precisely to what extent the shiver is due to conscious thoughts, or whether he feels it just because he must; and the feeling may be due to what he remembers being told about snakes, in which case it would not be due to pure auto-suggestion.