[Footnote 8: The old French case (quoted by Macnish) of a woman, with a portion of her skull removed, whose brain bulged out during dreams but was motionless in dreamless sleep, as well as the more recent similar case known to Hammond (_Treatise on Insanity_, p. 233), supports the belief that the psychic activity which is not manifested in rememberable dreams is probably at the most of a very shadowy character. Even during waking life psychic activity often falls to a very low ebb; Beaunis, who has investigated this question ('Comment Fonctionne mon Cerveau,' _Revue Philosophique_, January 1909), describes a condition which he names 'psychic twilight' and regards as frequently occurring.] [Footnote 9: Lucretius long ago referred to the significance of this fact (lib. iv. vv. 988-994), and he stated that the hallucination persisted for a time even after the dog had awakened. I have never myself been able to see any trace of such hypnagogic hallucination or delusion in dogs who awake from dreams, though I have frequently looked for it; it always seems to me that the dog who seemingly awakes from a dream of hunting grasps the fireside facts of life around him immediately and easily.] [Footnote 10: This classification of the sources of dreams has, however, been generally accepted for little more than a century. At an earlier period it was not usually believed to cover the whole ground. Thus Des Laurens (A. Laurentius) in the sixteenth century, in his treatise on the Disease of Melancholy (insanity), says that there are three kinds of dreams: (1) of Nature (_i.e._ due to external causes); (2) of the mind (_i.e._ based on memories); and, above both these classes, (3) dreams from God and the devil.] [Footnote 11: M. W. Calkins, 'Statistics of Dreams,' _American Journal of Psychology_, April 1893.] CHAPTER II THE ELEMENTS OF DREAM LIFE The Spontaneous Procession of Dream Imagery--Its Kaleidoscopic Character--Attention in Dreams--Relation of Drug Visions and Hypnagogic Imagery to Dreaming--Colour in Dreams--The Fusion of Dream Imagery--Compared to Dissolving Views--Sources of the Imagery--Various types of Fusion--The Subconscious Element in Dreaming--Verbal Transformations as Links in Dream Imagery--The Reduplication of Visual Imagery in Motor and other Terms.