into a relaxation; out of which it as fuddenly recovers by a convulfive fpring. To illuftrate this; let us confider, that when we intend to fit on a chair, and find it much lower than we expected, the shock is very violent; much more violent than could be thought from fo flight a fall as the difference between one chair and another can poffibly make. If, after defcending a flight of stairs, we attempt inadvertently to take another step in the manner of the former ones, the fhock is extremely rude and disagreeable; and by no art can we cause fuch a fhock by the fame means when we expect and prepare for it. When I fay that this is owing to having the change made contrary to expectation; I do not mean folely, when the mind expects. I mean likewise, that when an organ of fenfe is for fome time affected in fome one manner, if it be fuddenly affected otherwise, there enfues a convulfive motion; fuch a convulfion as is caused when any thing happens against the expectance of the mind. And though it may appear ftrange that such a change as produces a relaxation, should immediately produce a fudden convulfion; it is yet moft certainly fo, and fo in all the fenfes, Every one knows that fleep is a relaxation; and that filence, where nothing keeps the organs of hearing in action, is in general fittest to bring on this relaxation; yet when a fort of murmuring founds difpofe a man to fleep, let these sounds cease

fuddenly,

fuddenly, and the person immediately awakes; that is, the parts are braced up fuddenly, and he awakes. This I have often experienced myself, and I have heard the fame from obferving perfons. In like manner, if a person in broad day-light were falling asleep, to introduce a fudden darknefs would prevent his fleep for that time, though filence and darkness in themselves, and 'not fuddenly introduced, are very favourable to it. This I knew only by conjecture on the analogy of the senses when I firft digefted thefe obfervations; but I have fince experienced it. And I have often experienced, and fo have a thoufand others, that on the first inclining toward fleep,we have been fuddenly awakened with a moft violent ftart; and that this ftart was generally preceded by a fort of dream of our falling down a precipice: whence does this ftrange motion arife, but from the too fudden relaxation of the body, which by some mechanism in nature restores itself by as quick and vigorous an exertion of the contracting power of the muscles! The dream itself is caused by this relaxation; and it is of too uniform a nature to be attributed to any other caufe. The parts relax too fuddenly, which is in the nature of falling; and this accident of the body induces this image in the mind. When we are in a confirmed state of health and vigour, as all changes are then lefs fudden, and lefs on the extreme, we can feldom complain of this difagreeable fenfation.

SECT.

SECT. XVIII.

THE EFFECTS OF BLACKNESS MODERATED.

THOUGH the effects of black be painful origi nally, we must not think they always continue fo. Cuftom reconciles us to every thing. After we have been used to the fight of black objects, the terrour abates, and the smoothness and gloffinefs or fome agreeable accident of bodies fo coloured, foftens in fome measure the horrour and fternness of their original nature; yet the nature of their original impreffion ftill continues. Black will always have fomething melancholy in it, because the sensory will always find the change to it from other colours too violent; or if it occupy the whole compafs of the fight, it will then be darknefs; and what was faid of darknefs will be applicable here. I do not purpose to go into all that might be faid to illuftrate this theory of the effects of light and darknefs; neither will I examine all the different effects produced by the various modifications and mixtures of these two caufes. If the foregoing obfervations have any foundation in nature, I conceive them very fufficient to account for all the phænomena that can arife from all the combinations of black with other colours. To enter into every particular, or to anfwer every objection, would be an endless labour,

We

We have only followed the most leading roads; and we shall obferve the fame conduct in our inquiry into the cause of beauty.

SECT. XIX.

THE PHYSICAL CAUSE OF LOVE.

WHEN we have before us fuch objects as excite love and complacency; the body is affected, fo far as I could obferve, much in the following manner: The head reclines fomething on one fide; the eyelids are more closed than usual, and the eyes roll gently with an inclination to the object; the mouth is a little opened, and the breath drawn flowly, with now and then a low figh; the whole body is compofed, and the hands fall idly to the fides. All this is accompanied with an inward fense of melting and languor. These appearances are always proportioned to the degree of beauty in the object, and of fenfibility in the obferver. And this gradation from the highest pitch of beauty and fenfibility, even to the loweft of mediocrity and indifference, and their correfpondent effects, ought to be kept in view, else this defcription will feem exaggerated, which it certainly is not. But from this defcription it is almost impoffible not to conclude, that beauty acts by relaxing the folids of the whole fyftem. There are all the appearances of fuch a relaxation; and a relaxation fomewhat

fomewhat below the natural tone feems to me to be the cause of all pofitive pleafure. Who is a ftranger to that manner of expreffion so common in all times and in all countries, of being foftened, relaxed, enervated, diffolved, melted away by pleafure? The univerfal voice of mankind, faithful to their feelings, concurs in affirming this uniform and general effect: and although fome odd and particular inftance may perhaps be found, wherein there appears a confiderable degree of pofitive pleasure, without all the characters of relaxation, we must not therefore reject the conclufion we had drawn from a concurrence of many experiments; but we must still retain it, fubjoining the exceptions which may occur according to the judicious rule laid down by Sir Ifaac Newton in the third book of his Opticks. Our pofition will, I conceive, appear confirmed beyond any reafonable doubt, if we can fhew that fuch things as we have already obferved to be the genuine conftituents of beauty, have each of them, separately taken, a natural tendency to relax the fibres. And if it must be allowed us, that the appearance of the human body, when all these conftituents are united together before the fenfory, further favours this opinion, we may venture, I believe, to conclude, that the paffion called love is produced by this relaxation. By the fame method of reafoning which we have used in the inquiry into

the