firft the Genus or general Nature of it, which is a Reprefentation; and herein it agrees with many other Things, as a Statue, a Shadow, a Print, a verbal Defcription of a Man, &c. Then we confider wherein it differs from these, and we find it differs from a verbal Defcription in that it is a Reprefentation to the Eye and not to the Ear: It dif fers from a Statue in that it is a Reprefentation upon a flat Surface, and not in a folid Figure: It differs from a Shadow in that it is an abiding Representation and not a fleeting one: It differs from a Print or Draught, because it represents the Colours by Paint as well as the Shape of the Object by Delineation. Now fo many, or rather fo few of these Ideas put together, as are juft fufficient to diftinguifh a Picture from all other Reprefentations, make up its effential Difference or its Special Nature; and all these are included in its being painted on a plain Surface. Then join this to the Genus, which is a Reprefentation; and thus you have the compleat Definition of the Picture of a Man, viz. it is the Representation of a Man in Paint upon a Surface (or a Plane.)

Here it must be obferved, that when we speak of the Genus and Difference as compofing a Definition, it must always be understood that the neareft Genus and the fpecifick Difference are requi

red.

The next general Nature or the nearest Genus must be used in a Definition, because it includes all the reft ; as if I would define Wine, I muft fay Wine is a Juice, which is the nearest Genus; and not fay, Wine is a Liquid, which is a remote general Nature; or Wine is a Substance, which is yet more remote, for Juice includes both Substance and Liquid. Befides, neither of thefe two remote general Natures would make

any

any Distinction betwixt Wine and a thousand other Substances, or other Liquids, a remote Genus leaves the thing too much undistinguish'd.

The fpecifick Difference is that primary Attribute which diftinguishes each Species from one another, while they ftand ranked under the fame general Nature or Genus. Tho' Wine differs from other Liquids in that it is the Juice of a certain Fruit, yet this is but a general or generick Difference, for it does not diftinguifh Wine from Cyder or Perry; the Specifick Difference of Wine therefore is its Preffure from the Grape, as Cyder is preffed from Apples, and Perry from Pears.

In Definitions also we must use the primary Attribute that distinguishes the Species or special Nature, and not attempt to define Wine by its particular Taftes, or Effects, or other Properties, which are but fecondary or confequential, when its Preffure from the Grape is the most obvious and primary Distinction of it from all other Juices. I confefs in fome Cafes it is not fo easily known which is the primary Idea that distinguishes one thing from another; and therefore fome would as foon define Winter by the Coldness of the Seafon, as by the Shortness of the Days; though the Shortnefs of the Days is doubtlefs the moft juft, primary and philofophical Difference betwixt that and the other Seasons of the Year, fince Winter Days are always fhorteft, but not always the coldeft; I add alfo, that the Shortness of the Days is one Caufe of the Coldness, but the Cold is no Cause of their Shortnefs.

SECT

SECT. V.

Rules of Definition of the thing.

THE Special Rules of a good Definition are

Rule I. A Definition must be universal, or as some call it, adequate ; that is, it must agree to all the particular Species or Individuals that are included under the same Idea ; so the Juice of a Grape agrees to all proper Wines, whether Red, White, French, Spanish, Florence, &c.

Rule II. It must be proper and peculiar to the Thing defined, and agree to that alone; for it is the very Design of a Definition effectually to distinguish one thing from all others : So the Juice of a Grape agrees to no other Substance, to no other Liquid, to no other Being but Wine.

These two Rules being observed will always render a Definition reciprocal with the Thing defined ; which is a scholastick Way of speaking, to signify that the Definition may be used in any Sentence in the Place of the thing defined, or they may be mutually affirmed concerning each other, or substituted in the room of each other. The Juice of the Grape is Wine, or Wine is the Juice of the Grape. And wheresoever the Word Wine is used, you may put the Juice of the Grape instead of it, except when you consider Wine rather as a Word , than a Thing, or when it is mentioned in such logical Rules.

Rule

1

1

1

Rule III. A Definition ought to be clear and plain; for the Design of it is to lead us into the Knowledge of the Thing defined.

Hence it will follow that the Words used in a Definition ought not to be doubtful, and equivocal, and obscure, but as plain and easy as the Language will afford : And indeed it is a general Rule concerning the Definition both of Names and Things, that no Word should be used in either of them which has any Darkness or Difficulty in it, unless it has been before explain’d or defined.

Hence it will follow also, that there are many Things which cannot well be defined either as to the Name or the Thing, unless it be by synonymous Words, or by a Negation of the contrary Idea, &c. for learned Men know not how to make them more evident or more intelligible than the Ideas which every Man has gained by the vulgar Methods of teaching. Such are the Ideas of Extension, Duration, Thought, Consciousness, and most of our simple Ideas, and particularly sensible Qualities, as White, Blue, Red, Cold, Heat, Shrill, Bitter, Sour, &c.

We can say of Duration that it is a Continuance in Being, or a not ceasing to be ; we can say of Consciousness, that it is as it were a

that it is as it were a Feeling within our selves ; we may say Heat is that which is not Cold; or Sour is that which is like Vinegar ; or we may point to the clear Sky, and say that is Blue. These are the vulgar Methods of teaching the Definitions of Names, or Meaning of Words. But there are some Philosophers whose Attempt to define these Things learnedly have wrapt up their Ideas in greater Darkness, and exposed themselves to Ridicule and Contempt; as when they define Heat they say, it is Qualitas congregans ho

mogenea & fegregans keterogenea, i. e. a Quality gathering together Things of the fame Kind, and feparating Things of a different Kind. So they define White, a Colour arifing from the Prevalence of Brightness: But every Child knows Hot and White better without thefe Definitions.

There are many other Definitions given by the peripatetick Philofophers, which are very faulty by reafon of their Obfcurity; as Motion is defined by them the Act of a Being in Power fo far forth as it is in Power. Time is the Measure or Number of Motion according to past, present and future. The Soul is the Act of an organical natural Body, having Life in Power; and feveral others of the fame Stamp.

Rule IV. It is alfo conmonly prescribed amongst the Rules of Definition, that it should be fort, fo that it must have no Tautology in it, nor any Words fuperfluous. I confefs Definitions ought to be expreffed in as few Words as is confiftent with a clear and juft Explication of the Nature of the Thing defined, and a Diftinction of it from all other Things befide: But it is of much more Importance, and far better, that a Definition fhould explain clearly the Subject we treat of, tho' the Words be many, than to leave Obfcurities in the Sentence, by confining it within too narrow Limits. So in the Definition which we have given of Logick, that it is the Art of using Reafon well in the Search after Truth and the Communication of it to others, it has indeed many Words in it, but it could not well be shorter. Art is the Genus wherein it agrees with Rhetorick, Poefy, Arithmetick, Wrestling, Sailing, Building, &c. for all these are Arts alfo: But the Difference or fpecial Nature of it is drawn from its Object, Rea

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