and these bring on Sleep. It may be only calculated in general, that a Person, in a good State of Health, within twenty-four Hours, collects a Sufficiency for the Actions of fixteen wakeful Hours; so that he is to allow himself eight, or at least feven or fix quiefcent Hours, during which the Expences of Spirits ceafes, for the Filtration of new Supplies of nervous Juice; accordingly it is feldom that the Sleep of Perfons, not given to Indulgence or Sluggifhnefs, exceeds that Number of Hours. To conclude, Vigilancy is the Time of Wafte, Sleep the Time of Recruit; whatever Faintness or Pain the Body feels by fevere Labour and Fatigue, after a good Night's Reft, every Disorder is difperfed; it feels itself as it were renewed. The Fibres of the Muscles, by exceffive Labour, are ftretched nearly to a Degree of Rupture and Laceration, hence Laffitude and Pain; in the Night they relax, they become equally filled, and thus recover their natural Tone and Vigour : Tu O domitor Somne malorum, requies animi, Sleep Sleep, that knits up the ravell'd Sleeve of Care; The Death of each Day's Life, fore Labour's Bath, Balm of hurt Minds, great Nature's fecond Course, Chief Nourisher in Life's Feast. Macbeth. ESSAY ESSAY O N DREAM S. I HERE propofe to confider the State of the Soul during that Part of Life which we are under an indispensable Neceffity of confecrating to Quiefcence. The Undertaking, indeed, has its Difficulties, as the Soul is to be followed in Circumstances, where it feems defirous of concealing its March from us; and the Rationale is to be given of a State apparently fo ftrange; in which the Soul has Ideas without any reflective Knowledge of them; perceives Senfations, though under no external Impreffion; imagines Objects, conveys itself into Places, converses with Perfons which it never faw, and exercises no Controul on all these Phantoms, which, without the leaft Influence from itself, make their Appearance, or vanish, and affect it with Pleasure or Pain. Such is the State of Dreaming and that I may D not, not, with my Reflections, mingle any philofophic Dreams, any vague and precarious Hypotheses, I fhall confine myself to the Path of Experience; and, from the very Display of the Phenomena which accompany Dreaming, fhall endeavour to exhibit their Caufes and Origin. My Poftulatum is, that the Soul and Body are diftinct; and to offer any Proofs of it would be a needlefs Digreffion from my Subject. This Diftinction is fuch, that the Soul has its Train of Ideas and Operations produced by its peculiar Force, whilft the Body, likewife, has a Train of Determinations and Actions, which are executed according to the Laws of Motion, in a Manner fuitable to the Structure of its Organisation; no matter whether this be done by phyfical Influence, occafional Causes, or the pre-established Harmony. Whichfoever of these three Hypothefes I fhould adopt, it will throw no manner of Light on the Nature itself of the Facts. The only Point incontestable, being founded on Experience, is that the Soul, though a diftinct Substance from the Body, has, a real or apparent Connection or Intercourfe with it, by which certain Impreffions, admitted into the Body, certain Motions excited there, feem convey'd to the Soul, and there con 3 stantly ftantly produce correfpondent Ideas; whilft, reciprocally, certain Ideas, certain States of the Soul, occafion, in the Body, Motions of a determined Kind. It is from hence I take my Departure in explaining Dreams, and Experience is the only Clew which can guide me through this Labyrinth; but, previously, I must from this general Source of Experience draw feveral diftinct Principles neceffary to the Elucidation of the Subject before me. Of all the constituent Parts of our Machine, the Nerves alone are the Seat of Senfation. Whilft they preferve their Tenfion, and that precious Extract, that fubtile Liquor, formed in the Laboratory of the Brain, courfes, without Interruption, from the Origin of the Nerves to their Extremities; no Impreffion of any Force can be made on our Body, the whole Surface of which is interwoven with Nerves; but this Impreffion will, with an inconceivable Rapidity, pafs from the external to the internal Extremities, and instantaneoufly produce the Idea of a Senfation. I faid of an Impreffion of any Force, there being, indeed, an Infinity of fine and subtile Bodies floating about us, without affecting us; because, as they find a free Paffage through the Pores of our nervous Parts, they do not stir them; the Air itself, |