400. In the two preceding chapters I have reviewed the main disturbances and alternations of man's personality, and have then considered the norm of the waking phase of that personality. The sleeping phase must now be discussed; - what its characteristics are, how its special faculties can be developed, and what light the study of its manifestations may throw upon the constitution of man.

401. A physiological definition of sleep has never yet been achieved, and is rendered increasingly difficult by what we now know of hypnotic sleep; induced in apparent independence of the supposed physiological requisites of slumber.

402. On the psychological side, sleep is the suspension of waking consciousness. But this is only a negative definition. We must seek its positive characteristics, regarding it as a secondary personality. The abeyance of the supraliminal life may be the liberation of the subliminal.

403. To begin with, the mere break of waking consciousness is somehow associated with a potent physiological change - of a kind whose induction lies beyond the spectrum of our ordinary consciousness.

404. And when we pass on within the limits of powers consciously exercised in waking hours, we find that sleep, although it habitually suspends, yet does occasionally enhance those powers. Thus muscular control is enhanced in somnambulism.

405. And the power of visualisation is heightened in illusions hypnago-giques, - inward vision on the verge of sleep.

406. And also in hypnopompic pictures, - or the prolongation of dream-images into waking life.

407. Sometimes sensory imagination, inward vision, inward audition, and the like, - seem to be heightened and intensified in dream. 407 A. Case of Dr. Hodgson.

408. R. L. Stevenson utilised this sleep-faculty by self-suggestion to secure visual and dramatic interest for imagined scenes.

409. And similarly, as though by an unwilled self-suggestion, a dream may leave permanent nervous injury, or nervous benefit. 409 A. Faure's case. 409 B. Case of Dr. Holbrook.

410. Even stigmata may apparently be caused by self-suggestion in sleep: Krafft-Ebing's case.

411. Dream-memory and hypnotic memory seem to be connected; - suggesting some subliminal continuity of memory through all phases of personality.

412. And in fact we find that, where the memories of several states can be compared, it is the memory furthest from waking life whose span is generally the widest.

413. And dream-memory does at least sometimes include ecmnesic periods, as a case of Charcot's shows.

414. Dream-memory may include facts once known but now forgotten; and also facts which have indeed fallen within the sensory field, but which waking attention has never observed.

415. Example from Delbceuf of the recovery in dream of a forgotten memory. Cases of: 415 A. Mrs. Bickford-Smith. 415 B. Col. A. v. S.

416. Example of the recovery through dream of an object whose position seemed beyond the range of waking myopic vision: Case of Mr. Lewis.

417. Examples of dreams which reason as well as remember. 417 A. Davey's case. 417 B. Case of Professor Lamberton. 417 C. Case of Professor Hilprecht.

418. Analogy between the achievements of dream and the achievements of genius. Possibility that sleep may stand in closer relation than vigilance to a spiritual environment. Ancient universality of this belief.

419. Both teloesthesia and telepathy, - terms between which we may roughly divide our first groups of supernormal faculty, - meet us indistinguish-ably in the phenomena of dream. Other groups, as premonitions, present further difficulties for any logical scheme of classification.

420. Nor can the distinction between excursive dreams and receptive dreams serve as a definite mark of division. A fuller scheme will be discussed in Chapter VI (Sensory Automatism). For the present we shall take first those phenomena most nearly allied to our ordinary perceptions of the material world, and shall proceed to those which suggest relations to a spiritual world.

421. Visions of objects during sleep, no longer explicable as revivals of facts which had once fallen, though unnoticed, within the field of vision, but suggesting supernormal perception or excursion by the dreamer. Cases of:

421 A. Mr. Squires. 421 B. Mr. Watts. 421 C. Mrs. Wilkie. 421 D. Judge Howe. 421 E. Mr. Brighten. 421 P. Captain Scott. 421 G. Miss Luke. 421 H. Sir L. Jones. 421 J. Mr. Nascimento.

422. Cases where there is an apparently telepathic link between the dreamer and the scene discerned: - Case of Canon Warburton. Cases of:

422 A. Mrs. West. 422 B. Sir J. Drummond Hay.

423. Case of Mr. Boyle: vision of a death-scene.

424. Case of Sir E. Hamilton: dream of injury to brother's arm. Cases of: 424 A. Mr. Crewdson. 424B. Mrs. Richardson. 424 C. Mr. William Tudor.

425. Precognitive dreams. Indeterminate whether due to the subliminal self of the dreamer or to other spirits incarnate or discarnate. Case of Duchess of Hamilton. Cases of: 425 A. Mr. Pratt. 425 B. Mr. Ivey. 425 C. Lady Z. 425 D. Mr. Haggard. 425 E. Lady Q.

426. Prolonged vision of a scene of death: 426 A. Case of Dr. Bruce.

427. Case of Mrs. Storie. Symbolical presentation of a scene of death.

428. Illustrations of the theory of "psychical invasion " by the spirits of living persons: case of Mrs. T. Cases of: 428 A. Mr. Pike. 428 B. Mrs. Manning. 428 C. Mr. Newnham. 428 D. Mr. W. 428 E. Mrs. Shagren. 428 F. Mrs. Venter.

429. Sometimes this invasion appears to come from departed spirits. Cases of: 429 A. Mrs. Menneer. 429 B. Mrs. Lightfoot. 429 C. Mr. Wing-field. 429 D. Mrs. Green. 429 E. Mr. Dignowity. 429 F. Professor Dolbear.

430. Summary of the lines of inquiry dealt with in the preceding sections, and the conclusion suggested that the self of sleep is a spirit freed from ordinary material limitations.

431. This conclusion accords with the hypothesis that we are living a life in two worlds. The waking personality is adapted to the needs of earthly life; the personality of sleep maintains the fundamental connection between the organism and the spiritual world by supplying it with spiritual energy during sleep, and itself develops by the exercise of its own spiritual faculties.

432. This conclusion will be further justified in later chapters, and especially in those dealing with states analogous to sleep; somnambulistic and hypnotic trance - possession and ecstasy.