The most frivolous pastimes have now a habit of degenerating into scientific exercises. Croquet was ruined, as a form of lounging, by the precision attained by some players; lawn-tennis is a serious affair; and even ghost stories, the delight of Christmas Eve, have been ravaged and annex ed by psychology. True, there are some who aver that the science of the Psychical Society does not hold water; but, in any case, it is as dull and difficult as if it were some orthodox research dear to Mr Herbert Spencer. To prove this fact, I had marked for quotation some remarks, by eminent ghost-hunters, on the provinces and parts of the brain, on the subjective and the objective, the conscious, the reflex, the automatic, – tout le tremblement, as we may well say, – which would frighten off the most intrepid amateurs. ‘The oldest aunt’ would forget ‘the saddest tale,’ if plied with remarks on the ‘dextro-cerebral hemisphere’ of the brain. If we must understand all that kind of thing before we can enjoy a ghost story, we who are middle-aged may despair. But I hope to give the gist of what psychological science (if it is a science) has to say about the existence of a bogie, and to do so without overtaxing intellects about the average. Science has tackled this theme before. By aid of about two cases of hallucination, Nicolai's and ‘Mrs A.'s’ (whoever Mrs A. may have been), Ferrier and Hibbert decided that ghosts were merely ‘hallucinations,’ ‘revived impressions.’ Very good; but hallucinations caused by what? and wherefore so frequently coincident with the death of the person who seems to be seen? I ventured to ask these questions long ago in the article on ‘Apparitions’ in the ‘Encyclopædia Britannica.’ A good many years have elapsed since I bleated out my artless amateur theories of the ghostly, and incurred the censure, I think, of Dr Maudsley and other serious persons. Yet I was serious enough in holding that the explanation of all ghosts as casual hallucinations was too attenuated. Materials were scanty then, – mere tales of one's grandmother, and legends in old books concerned with what was called ‘the Supernatural.’