I. By Senfes, I mean thofe Faculties whereby we are enabled to discern and know fuch particular Objects as are prefent. These are either,

1. Outward, By which we can apprehend external Objects, as when we fee, or hear, or touch any Thing prefented to us.

2. Inward, By which we can difcern internal Objects, and are conscious to our felves, or fenfible both of the Impreffions that are made upon our outward Senfes, and of the inward Motions of our Minds; namely, our Apprehenfions, Inclinations, and the Power of determining our felves, as to our own Actions; and by which we can at any time be affured of what we think, or what we defire or purpose.

II. By Understanding, I mean that Faculty whereby we are enabled to apprehend the Objects of Knowledge, Generals as well as Particulars, Abfent Things as well as Prefent; and to judge of their Truth or Falfhood, Good or Evil.

That kind of Evidence may be faid to arise from the Nature of Things, when there is fuch a Congruity or Incongruity betwixt the Terms of a Propofition, or the Deductions of one Propofition from another, as doth either fatisfy the Mind, or elfe leave it in doubt and hesitation about them.

That kind of Evidence is faid to arife front Teftimony, when we depend upon the Credit

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and Relation of others for the Truth or Falfhood of any Thing. There being several Things which we cannot otherwise know, but as others do inform us of them. As namely Matters of Fact, together with the Account of Perfons and Places at a Distance. Which kind of Evidence will be more or lefs clear, according to the Authority and Credit of the Witness.

Besides these, there is a mixed kind of Evidence relating both to the Senfes and Underftanding, depending upon our own Obfervation and repeated Trials of the Iffues and Events of Actions or Things, called Experience.

These are the feveral kinds of Evidence whereby we attain to the Knowledge or Belief of Things.

The Kinds of Affent proceeding from them, are reducible to these Two Heads.

I. Knowledge or Certainty, which may be diftinguished into three Kinds, which I crave leave to call by the Names of Phyfical. Mathematical.

Moral.

II. Opinion or Probability.

I. That kind of Affent which doth arise from fuch plain and clear Evidence as doth not admit of any reasonable Cause of doubting, is called Knowledge or Certainty.

1. I

1. I call that Phyfical Certainty which doth depend upon the Evidence of Senfe, which is the first and highest Kind of Evidence of which human Nature is capable.

Nothing can be more manifeft and plain to me, than that I now fee fomewhat which hath the Appearance of fuch a Colour or Figure, than that I have in my mind fuch a Thought, Defire, or Purpose, and do feel within my felf a certain Power of determining my own Actions, which is called Liberty.

To fay that we cannot tell whether we have Liberty, because we do not understand the manner of Volition, is all one as to say, that we cannot tell whether we fee or hear, becaufe we do not understand the manner of Senfation.

He that would go about to confute me in any of these Apprehenfions, ought to bring a Medium that is better known, and to derive his Argument from fomewhat that is more evident and certain than these Things are, unlefs he can think to overthrow and confute that which is more plain and certain, by that which is lefs plain and certain; which is all one as to go about to out-weigh a heavy Body by fomewhat that is lighter, or to attempt the proving of Ten to be more than Eleven; than which nothing can be more abfurd.

2. I call that Mathematical Certainty, which doth more eminently belong to Ma thematical Things, not intending hereby to B 3

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exclude fuch other Matters as are capable of the like Certainty; namely, all fuch fimple abstracted Beings, as in their own Natures do lie fo open, and are fo obvious to the Underftanding, that every Man's Judgment (though never fo much prejudiced) muft neceffarily affent to them. 'Tis not poffible for any Man in his Wits (though never fo much addicted to Paradoxes) to believe otherwife, but that the Whole is greater than the Part That Contradictions cannot be both true; That three and three make fix; That four is more than three.

There is fuch a kind of Connexion betwixt the Terms of fome Propofitions, and fome Deductions are fo neceffary as must unavoidably enforce our Affent. There being an evident Neceffity that fome Things must be fo, or not fo, according as they are affirmed or denied to be, and that fuppofing our Faculties to be true, they cannot poffibly be otherwife, without implying a Contradiction.

3. I call that Moral Certainty, which hath for its Object such Beings as are less fimple, and do more depend upon mixed Circumftances. Which though they are not capable of the fame kind of Evidence with the former, fo as to neceffitate every Man's Af fent, though his Judgment be never fo much prejudiced against them; yet may they be fo plain, that every Man whofe Judgment is free from prejudice will confent unto them.

And

And though there be no natural Neceffity, that fuch things must be so, and that they cannot poffibly be otherwife, without implying a Contradiction; yet may they be fo certain as not to admit of any reasonable Doubt concerning them.

Under each of thefe Heads there are feveral Propofitions, which may be ftiled Selfevident and firft Principles.

Self-evident, Because they are of themfelyes fo plain, as not to be capable of proof from any Thing that is clearer or more known.

First Principles, Because they cannot be proved a priori; That which is first can have nothing before it.

Only they may receive fome kind of Illuftration by Inftances and Circumstances, and by fuch univerfal Effects as do proceed from them; and from the monftrous Abfurdities that will follow upon the denial of them.

Such Deductions as do neceffarily flow from thefe Principles, have the fame kind of Certainty, whether Phyfical, Mathematical, or Moral, with the Principles themselves from which they are deduced.

The two firft of thefe, namely, Phyfical and Mathematical Certainty may be filed Infallible; and Moral Certainty may properly be ftiled Indubitable.