increafes. To this caufe is to be afcribed, in part, the effect which the dread of spirits in the dark, has on fome perfons, who are fully convinced in fpeculation, that their apprehenfions are groundless; and to this alfo is owing, the effect of any accidental perception in giving them a momentary relief from their terrors. Hence the remedy which nature points out to us, when we find ourselves overpowered by imagination. If every thing around us be filent, we endeavor to create a noife, by speaking aloud, or beating with our feet; that is, we ftrive to divert the attention from the fubjects of our imagination, by prefenting an object to our powers of perception. The conclufion which I draw from thefe obfervations is, that, as there is no state of the body in which our perceptive powers are fo totally unemployed as in fleep, it is natural to think, that the objects which we conceive or imagine, must then make an impreffion on the mind, beyond comparifon greater, than any thing of which we can have. experience while awake.

From these principles may be derived a fimple, and, I think, a fatisfactory explanation of what fome writers have reprefented as the most mysterious of all the circumftances connected with dreaming; the inaccurate estimates we are apt to form of Time, while we are thus employed; an inaccuracy which fometimes extends fo far, as to give to a single inftance, the appearance of hours, or perhaps of days. A fudden noife, for example, fuggefts a dream connected with that perception; and, the moment afterwards, this noise has the effect of awaking us; and yet, during that momentary interval, a long feries of circumftances has paffed before the imagination. The ftory quoted by Mr. Addifon* from the Turkish Tales, of the Miracle wrought by a Mahometam

* SPECTATOR, No. 94.

Doctor, to convince an infidel Sultan, is, in fuch cafes, nearly verified.

The facts I allude to at prefent are generally explained by fuppofing, that, in our dreams, the rapdiity of thought is greater than while we are awake: but there is no neceffity for having recourse to fuch a fuppofition. The rapidity of thought is, at all times fuch, that, in the twinkling of an eye, a crowd of ideas may pass before us, to which it would require a long difcourse to give utterance; and tranf actions may be conceived, which it would require days to realize. But, in fleep, the conceptions of the mind are mistaken for realities; and therefore, our estimates of time will be formed, not according to our experience of the rapidity of thought, but according to our experience of the time requifite for realizing what we conceive. Something perfectly analogous to this may be remarked in the perceptions we obtain by the sense of fight. When I look into a fhew-box, where the deception is imperfect, I fee only a set of paltry daubings of a few inches diameter; but, if the representation be executed with so much skill, as to convey to me the idea of a diftant profpect, every object before me fwells in its dimensions, in proportion to the extent of space which I conceive it to occupy; and what feemed before to be shut up within the limits of a small wooden frame, is magnified, in my apprehenfion, to an immenfe landscape of woods, rivers, and mountains.

The phenomena which we have hitherto explained, take place when fleep feems to be complete; that is, when the mind lofes its influence over all thofe powers whofe exercife depends on its will. There are, however, many cafes in which fleep feems to be partial; that is, when the mind lofes its influence over fome powers, and retains it over others. In the cafe of the fomnambuli, it retains its power over the limbs, but it poffeffes no influence over its own

thoughts, and scarcely any over the body; excepting thofe particular members of it which are employed in walking. In madness, the power of the will over the body remains undiminished, while its influence in regulating the train of thought is in a great meafure fufpended; either in confequence of a particular idea, which engroffes the attention, to the exclufion of every thing else, and which we find it impoffible to banish by our efforts; or in confequence of our thoughts fucceeding each other with fuch rapidity, that we are unable to ftop the train. In both of these kinds of madness, it is worthy of remark, that the conceptions or imaginations of the mind becoming independent of our will, they are apt to be miftaken for actual perceptions, and to affect us in the fame manner.

By means of this fuppofition of a partial sleep, any apparent exceptions which the hiftory of dreams may afford to the general principles already stated, admit of an eafy explanation.

Upon reviewing the foregoing obfervations, it does not occur to me, that I have in any inftance tranfgreffed thofe rules of philofophifing, which, fince the time of Newton, are commonly appealed to, as the tests of found investigation. For, in the first place, I have not fuppofed any caufes which are not known to exift; and fecondly, I have fhewn, that the phenomena under our confideration are neceffary confequences of the caufes to which I have referred them. I have not fuppofed, that the mind acquires in fleep, any new faculty of which we are not confcious while awake; but only (what we know to be a fact) that it retains fome of its powers, while the exercise of others is fufpended: and I have deduced fynthetically, the known phenomena of dreaming, from the operation of a particular clafs of our faculties, unconnected by the operation of another. I flatter myself, therefore, that this inquiry will not

PP

only throw fome light on the ftate of the mind in 1 fleep; but that it will have a tendency to illuftrate the mutual adaptation and subferviency which exifts among the different parts of our conftitution, when we are in a complete poffeffion of all the faculties and principles which belong to our nature.*

CHAPTER FIFTH.

PART SECOND.

Of the Influence of Affociation on the Intellectual and on the Active Powers.

SECTION I.

Of the Influence of cafual Affociations on our fpeculative Conclufions.

THE Affociation of Ideas has a tendency to warp our speculative opinions chiefly in the three following ways:

First, by blending together in our apprehenfions, things which are really diftinct in their nature; fo as to introduce perplexity and error into every procefs of reasoning in which they are involved.

Secondly, by mifleading us in thofe anticipations of the future from the past, which our conftitution difpofes us to form, and which are the great foundation of our conduct in life.

Thirdly, by connecting in the mind erroneous

* See Note [0.]

opinions, with truths which irresistibly command our affent, and which we feel to be of importance to human happiness.

A fhort illuftration of these remarks, will throw light on the origin of various prejudices; and may, perhaps, fuggeft fome practical hints with respect to the conduct of the understanding.

I. I formerly had occafion to mention feveral inftances of very intimate affociations formed between two ideas which have no neceffary connection with each other. One of the most remarkable is, that which exists in every person's mind between the notions of colour and of extenfion. The former of these words expreffes (at least in the fenfe in which we' commonly employ it) a fenfation in the mind; the latter denotes a quality of an external object; so that there is, in fact, no more connection between the two notions than between thofe of pain and of folidity;* and yet, in confequence of our always perceiving extenfion, at the fame time at which the fenfation of colour is excited in the mind, we find it impoffible to think of that fenfation, without conceiving extenfion along with it.

Another intimate affociation is formed in every mind between the ideas of space and of time. When we think of an interval of duration, we always conceive it as fomething analogous to a line, and we apply the fame language to both fubjects. We speak of a long and fhort time, as well of a long and short distance, and we are not confcious of any metaphor in doing fo. Nay, so very perfect does the analogy appear to us, that Bofcovich mentions it as a curious circumftance, that extension should have three dimenfions, and duration only one.

This apprehended analogy seems be founded wholly on an affociation between the ideas of space

* See Note [P.]