but in the organ, or in the principle of perception which feels in that organ. When we fay that the food which we eat has an agree able or difagreeable tafte in every part of it, we do not thereby mean that it has the feeling or fenfation of taste in any part of it, but that in every part of it, it has the power of exciting that feeling or sensation in our palates. Though in this cafe we denote by the fame word (in the fame manner, and for the fame reafon, as in the case of heat and cold) both the fenfation and the power of exciting that sensation, this ambiguity of language misleads the natural judgments of mankind in the one cafe as little as in the other. Nobody ever fancies that our food feels its own agreeable or disagreeable taste.

Of the Senfe of SMELLING.

EVERY fmell or odour is naturally felt as in the noftrils; not as preffing upon or refifting the organ, not as in any respect external to, or independent of, the organ, but as altogether in the organ, and nowhere else but in the organ, or in the principle of perception which feels in that organ. We foon learn from experience, however, that this fenfation is commonly excited by fome external body; by a flower, for example, of which the ab

fence

fence removes, and the prefence brings back, the fenfation. This external body we confider as the caufe of this fenfation, and we denominate by the fame words both the fenfation and the power by which the external body produces this fenfation. But when we say that the smell is in the flower, we do not thereby mean that the flower itself has any feeling of the fenfation which, we feel; but that it has the power of exciting this fenfation in our noftrils, or in the principle of perception which feels in our noftrils. Though this fenfation, and the power by which it is excited, are thus denoted by the fame word, this ambiguity of language misleads, in this cafe, the natural judgments of mankind as little as in the two preceding.

Of the Senfe of HEARING.

EVERY found is naturally felt as in the Ear, the organ of Hearing. Sound is not naturally felt as refifting or preffing upon the organ, or as in any refpect external to, or independent of, the organ. We naturally feel it as an affection of our Ear, as fomething which is altogether in our Ear, and nowhere but in our Ear, or in the principle of perception which feels in our Ear. We foon learn from experience, indeed, that the fenfation is frequently

excited

excited by bodies at a confiderable distance from us; often at a much greater distance, than those ever are which excite the fenfation of Smelling. We learn too from experience that this found or fenfation in our Ears receives different modifications, according to the distance and direction of the body which originally causes it. The fenfation is stronger, the found is louder, when that body is near. The fenfation is weaker, the found is lower, when that body is at a diftance. The found, or fenfation, too undergoes fome variation according as the body is placed on the right hand or on the left, before or behind us. In common language we frequently fay, that the found feems to come from a great or from a fmall distance, from the right hand or from the left, from before or from behind us. We frequently fay too that we hear a found at a great or small distance, on our right hand or on our left. The real found, however, the fenfation in our ear, can never be heard or felt any where but in our ear, it can never change its place, it is incapable of motion, and can come, therefore, neither from the right nor from the left, neither from before nor from behind us. The Ear can feel or hear nowhere but where it is, and cannot ftretch out its powers of perception, either to a great or to a small distance, either to the right or to the left. By all fuch phrafes we

in reality mean nothing but to exprefs our opinion concerning either the distance, or the direction of the body, which excites the fenfation of found. When we fay that the found is in the bell, we do not mean that the bell hears its own found, or that any thing like our fenfation is in the bell, but that it poffeffes the power of exciting that sensation in our organ of Hearing. Though in this, as well as in fome other cafes, we express by the fame word, both the Sensation, and the Power of exciting that Senfation; this ambiguity of language occafions fcarce any confufion in the thought, and when the different meanings of the word are properly diftinguished, the opinions of the vulgar, and thofe of the phi lofopher, though apparently oppofite, turn out to be exactly the fame.

Thefe four claffes of fecondary qualities, as philofophers have called them, or to speak more properly, these four claffes of Senfations; Heat and Cold, Tafte, Smell, and Sound; being felt, not as refifting or preffing upon the organ; but as in the organ, are not natu rally perceived as external and independent fubftances; or even as qualities of fuch fubftances; but as mere affections of the organ, and what can exift nowhere but in the organ.

They do not poffefs, nor can we even conceive them as capable of poffeffing, any one of the qualities, which we confider as effential

to, and infeparable from, the external folid and independant fubftances.

First, They have no extenfion. They are neither long nor fhort; they are neither broad nor narrow; they are neither deep nor fhallow. The bodies which excite them, the spaces within which they may be perceived, may poffefs any of thofe dimenfions; but the Senfations themselves can poffefs none of them. When we fay of a Note in Mufic, that it is long or fhort, we mean that it is so in point of duration. In point of extenfion we cannot even conceive, that it should be either the one or the other.

Secondly, Thofe Senfations have no figure. They are neither round nor fquare, though the bodies which excite them, though the fpaces within which they may be perceived, may be either the one or the other.

Thirdly, Thofe Senfations are incapable of motion. The bodies which excite them may be moved to a greater or to a finaller distance. The Senfations become fainter in the one cafe, and ftronger in the other. Those bodies may change their direction with regard to the organ of Senfation. If the change be confiderable, the Senfations undergo fome fenfible variation in confequence of it. But ftill we never afcribe motion to the Senfations. Even when the perfon who feels any of thofe Senfations, and confequently the organ by