exteriour cause. Sensation is wholly within; but Perception carries us, as it were, out of ourselves, and makes us acquainted with the world around us. It is especially by means of this last power, that material nature, in all its varieties of form and beauty, is brought within the range of our inspection. If we had but sensation alone, there would still be form and fragrance, and colour, and harmony of sound, but it would seem to be wholly inward. The mind would then become not merely what Leibnitz supposed it to be, a mirror of the universe; it would be the universe itself; we could know no other world, no other form of being. Perception prevents the possibility of such a mistake; it undeceives and dissipates the flattering notion, that all things are in the soul; it leads us to other existences, and in particular to the knowledge of the vast and complicated fabric of the material creation.

§. 148. Of the primary and secondary qualities of matter.

From what has been said, it will be noticed, that SENSATION implies the existence of an external material world as its cause, and that PERCEPTION implies the same existence both as cause and object. As, therefore, the material world comes now so directly and closely under consideration, it seems proper briefly to revert to that subject. It is hardly necessary to repeat the sentiment, which has already been proposed and insisted on, that we are altogether ignorant of the subjective or real essence of matter. Our knowledge embraces merely its qualities or properties, and nothing more. Without proposing to enter into a minute examination of them, it will be proper to recall to recollection here, that the qualities of material bodies have been ranked by writers under the two heads of Primary and Secondary.

The PRIMARY QUALITIES are known by being essential to the existence of all bodies. They are extension, figure, divisibility, and solidity; and some writers have included motion. They are called PRIMARY for the reason already

distinctly referred to, that all men embrace them in the notions, which they form of matter, and that they are essential to its existence. All bodies have extension, all bodies have figure, all are capable of division, all possess the attribute of solidity.

By SOLIDITY in bodies, (perhaps some would prefer the term RESISTANCE,) is to be understood that quality, by which a body hinders the approach of others, between which it is interposed. In this sense even water, and all other fluids are solid. If particles of water could be prevented from separating, they would oppose so great resistance, that it would be impossible for any two bodies, between which they might be, to come in contact. This was shown in an experiment, which was once made at Florence. A quantity of water was inclosed in a gold ball, which on the most violent pressure could not be made to fill the internal cavity, until the water inside was forced through the pores.

There is reason also for that part of the arrangement, which includes DIVISIBILITY. We cannot conceive of a particle so small as not to be susceptible of division. And to that small particle must belong not only divisibility, but the qualities of solidity, extension, and figure.

§. 149. Of the secondary qualities of matter.

The SECONDARY qualities of bodies are of two kinds; (1) Those, which have relation to the perceiving and sentient mind; (2) Those, which have relation to other bodies.

Under the first class are to be included sound, colour,taste, smell, hardness and softness, heat and cold, roughness and smoothness. &c. When we say of a body it has sound, we imply in this remark, that it possesses qualities, which will cause certain effects in the mind; the term sound being applicable by the use of language both to the qualities of the external object, and to the effect produced within. When we say it has colour, we always make a like reference to the mind, which beholds and

contemplates it; and it is the same of the other secondary qualities of this description.

The other class of secondary qualities, (or properties as they are not unfrequently termed,) those which have relation to other material bodies, are exceedingly various and numerous. The material substance, which in relation to the mind possesses the qualities of sound and colour, may possess also in relation to other bodies the qualities or properties of malleability, fusibility, solubility, permeability, and the like.

§. 150. Of the nature of mental powers or faculties.

But we

We have spoken of Perception as a POWER of the mind, as well as a mental state or act. This is owing to the imperfection of language. The same term, at least in the English language, signifies both the result, and the corresponding power; and oftentimes there is nothing but the connection to determine which is meant. have recurred to this subject here, merely for the purpose of suggesting the importance of keeping in recollection,that mental powers, (what are otherwise called faculties and not unfrequently susceptibilities,) are not distinct from the mind itself. They are only the ability of the mind to act in a particular way. We apply the term also in other cases; we speak of the power or faculty of the MEMORY, of REASONING, of IMAGINATION, &c. Such expressions are found in all languages, and cannot well be avoided. They are brief, and, on the whole, convenient representations of the various ways, in which the soul is capable of acting, or exerting itself.

But while we keep in recollection, that powers or faculties are only the ability of the mind to act in a particular way, it is further to be noticed, that in most cases what are so called are complex in their nature; they are made up in their results of various simple feelings, and imply the exercise of more than one simple susceptibility. It is proper, therefore, to analyze them, and to become acquainted with their parts; otherwise our notions will be confused, and often erroneous. Still we cannot

wholly lay aside the expressions, which use and the wants of men have introduced; nor is this necessary, if we will but take the pains to explain the true nature of the operations, and of that ability of the mind, which they profess to represent. If philosophers should undertake to introduce a whole new system of terms, (and the credit is due to Kant that there is not wanting a notable instance of this in modern times,) still it would be necessary to employ the old ones, in order to make them understood by mankind generally. As a general rule it is better to employ the common and acknowledged phraseology, only taking care to limit and explain it so far as it may be liable to misapprehension in consequence of a new and scientific application. "It looks too much like affectation, (says Locke, speaking of these forms of speech,) wholly to lay them by; and philosophy itself, though it likes not a gaudy dress, yet when it appears in public, must have so much complacency, as to be clothed in the ordinary fashion and language of the country, so far as it can consist with truth and perspicuity,"

CHAPTER THIRD.

THE SENSES OF SMELL AND TASTE.

§. 151. Nature and importance of the senses as a source of knowledge.

It is desirable to keep clearly in the mind the precise relation of the senses to the origin, progress, and amount of our knowledge, and to possess if possible a correct understanding of their true value. In a certain sense the possession of the bodily organs, with which we are furnished, is not essential and pre-requisite to the possession of that knowledge, which we are accustomed to ascribe to them. There is nothing unwarrantable and unreasonable in the supposition, that the knowledge, which we now have by their means, might have been possessed without their aid, either immediately, or in some way altogether different. Their use and indispensableness in the acquisition of a certain portion of what men are permitted to know, is a matter of arrangement and appointment on the part of our Maker. It is undoubtedly an evidence of the correctness of this remark, that the Supreme Being has a full acquaintance with all those outward objects, which present themselves to our notice, without being indebted to any material instrumentality and mediation. He perceives in another way, or rather all knowledge is