I expressed my surprise, having never before heard of it. Then, again to my surprise, he poured rather copiously from the bottle on to a plate of food, saying, in explanation, that it was pleasant to take and not dangerous. This was a vivid morning dream, and on awakening I had no difficulty in detecting the source of its various minor details, especially a note received on the previous evening and containing a dubious figure, the precise nature of which I had used my pocket lens to determine. But what was selvdrolla, the most vivid element of the dream? I sought vainly among my recent memories, and had almost renounced the search when I recalled a large bottle of salad oil seen on the supper table the previous evening; not, indeed, resembling the dream bottle, but containing a precisely similar fluid. Selvdrolla was evidently a corruption of "salad oil." I select this dream to illustrate the uncertainty of dream consciousness, because it also illustrates at the same time the element of certainty in dream subconsciousness. Throughout my dream I remained, consciously, in entire ignorance as to the real nature of selvdrolla, yet a latent element in consciousness was all the time presenting it to me in ever-clearer imagery.
While the confusions of dreaming are usually the union of unconnected streams of imagery which have, as it were, come from widely remote parts of the memory system to strike together at the narrow focus of shaping consciousness, in some rarer cases the fused images are really suggested by analogy and are not accidental. Maury records successions of dream imagery strung together by verbal resemblances; I have found such dreams rare, but other forms of association fairly common. Thus I once dreamed that I was with a dentist who was about to extract a tooth from a patient. Before applying the forceps he remarked to me (at the same time setting fire to a perfumed cloth at the end of something like a broomstick in order to dissipate the unpleasant odor) that it was the largest tooth he had ever seen. When extracted I found that it was indeed enormous, in the shape of a caldron, with walls an inch thick. Taking from my pocket a tape measure (such as I always carry in waking life) I founds the diameter to be not less than twenty-five inches; the interior was like roughly hewn rock, and there were sea-weeds and lichenlike growths within. The size of the tooth seemed to me large, but not extraordinarily so. It is well known that pain in the teeth, or the dentist's manipulations, cause those organs to seem of extravagant extent; in dreams this tendency rules unchecked; thus a friend once dreamed that mice were playing about in a cavity in her tooth. But for the dream first quoted there was no known dental origin; it arose solely or chiefly from a walk during the previous afternoon among the rocks of the Cornish