[68] _Friend_, vol. i. p. 248. The story is referred to by Sir W. Scott in his _Demonology and Witchcraft_. [69] See E.B. Tylor, _Primitive Culture_, ch. xi.; _cf._ Herbert Spencer, _Principles of Sociology_, ch. x. [70] For a fuller account of the different modes of dream-interpretation, see my article "Dream," in the ninth edition of the _Encyclopaedia Britannica_. [71] For a fuller account of the reaction of dreams on waking consciousness, see Paul Radestock, _Schlaf und Traum_. The subject is touched on later, under the Illusions of Memory. [72] For an account of the latest physiological hypotheses as to the proximate cause of sleep, see Radestock, _op. cit._, appendix. [73] Plutarch, Locke, and others give instances of people who never dreamt. Lessing asserted of himself that he never knew what it was to dream. [74] The error touched on here will be fully dealt with under Illusions of Memory. [75] For a very full, fair, and thoughtful discussion of this whole question, see Radestock, _op. cit._, ch. iv. [76] This may be technically expressed by saying that the liminal intensity (Schwelle) is raised during sleep. [77] See Wundt, _Physiologische Psychologie_, pp. 188-191. [78] There is, indeed, sometimes an undertone of critical reflection, which is sufficient to produce a feeling of uncertainty and bewilderment, and in very rare cases to amount to a vague consciousness that the mental experience is a dream. [79] _Observations on Man_, Part I. ch. iii, sec. 5. [80] Quoted by Radestock, _op. cit._, p. 110. [81] _Le Sommeil et les Reves_, p. 132, _et seq._ [82] _Das Leben des Traumes_, p. 369. Other instances are related by Beattie and Abercrombie. [83] _Le Sommeil et les Reves_, p. 42, _et seq._ [84] _Beitraege sur Physiognosie und Heautognosie_, p. 256. For other cases see H. Meyer, _Physiologie der Nervenfaser_, p. 309; and Struempell, _Die Natur und Entstehung der Traeume_, p. 125. [85] A very clear and full account of these organic sensations, or common sensations, has recently appeared from the pen of A. Horwicz in the _Vierteljahrsschrift fuer wissenschaftliche Philosophie_, iv. Jahrgang 3tes Heft. [86] Schopenhauer uses this hypothesis in order to account for the apparent reality of dream-illusions. He thinks these internal sensations may be transformed by the "intuitive function" of the brain (by means of the "forms" of space, time, etc.) into quasi-realities, just as well as the subjective sensations of light, sound, etc., which arise in the organs of sense in the absence of external stimuli. (See _Versuch ueber das Geisterschen: Werke_, vol. v. p. 244, _et seq._) [87] _Das Alpdruecken_, pp. 8, 9, 27. [88] It is this fact which justifies writers in assigning a prognostic character to dreams.