I. Cogitation is the Rule of Truth. Wherefore there can be no more certain Rule of Truth than our Cogitation, so that the same be but distinct and clear, and without the least Doubtful∣ness; because it is impossible for us to mistake, as long as the Judgments we frame of any thing do correspond to our Perceptions. It being an un∣doubted Axiom with us, That our Knowing of a thing is a sure Argument of its Essence. Not as if because we perceive the Essence of any thing, that from thence we should presently conclude that it exists: But because it is impossible that any thing which is clearly known by us, should not be such as it is known by us; that is, the thing must exist, if its Existence be perceived by us, or must be of this or the other Nature, if its Nature be repre∣sented to our Mind.
II. From this Principle the Exi∣stence of GOD is proved. From this Principle Descartes evidently demon∣strates the Existence of GOD. For if upon the account only (saith he) that I have such an Idea in my Mind, it doth follow that whatsoever I perceive clearly and distinctly to belong to it, doth really do so; may I not from hence fetch an Argu∣ment for the Existence of God? Yes surely: For the Idea of GOD, represents a Being absolutely Perfect: Now it is every whit as repugnant to a Being absolutely Perfect, to want any Perfection, as for Example, Existence, as it is for a Triangle not to have three Angles equal to two right ones.
III. Provided it be clear and di∣stinct. I said in the Beginning, provided our Cogitation be clear and distinct; because no Certainty can be expected from a thing, whose Knowledge involves the least degree of Obscurity or Confusion. And therefore Plato in his Timaeus tells us, That when we discourse of a firm, stable, and intelligible thing, our Reasons also must be stable, immutable, and insuperable. For seeing that clear and distinct Knowledge is something which we our selves are not the Authors of, it must follow that GOD is the Author of the Connexion there is between clear and distinct Knowledge, and the assent which the Will infallibly yields to it. So that it is absolutely impossible, that what I thus apprehend to be true, should be false: As for Example, When I perceive Two and Four to be Six; that in a Triangle there be three Angles equal to two Right ones; and the like. It is impossible these should be false; not be∣cause they are so conceived by me, but because except they were true, I could never have clearly or distinctly perceiv'd them.
IV. It is im∣possible that what we clearly and distinctly perceive should be false. For if any thing thus apprehended by me could be false, this would destroy all Human Knowledge; neither could any of us be sure of any Truth, no not of the Existence of God, nor of any of those things which are related to us in Holy Writ: Since it might still be objected to us, that those very things may be false which we most clearly and distinctly perceive.
V. Knowledge arising from the Senses is Doubtful. But we cannot attain the same certainty of Know∣ledge in those things which are only perceived by the Senses, forasmuch as they are liable to Mistake: As when a Man, whose Eyes are deprav'd by a suffusion of Gall, takes all things he sees to be Yellow; and perceives the same as clearly, as those who see the true Colour of every thing.
VI. The cer∣tainty of our Percep∣tion de∣pends on the Under∣standing. It remains therefore, that all the Certainty we have, is only of those things which we apprehend with our Understanding. Neither doth it destroy this Rule, that some tell us they have sometimes been deceived even in those things which they thought to be most true, and which they were con••••dent they had clearly perceived. For this happens to them, because they derive the clearness of their Cogitation, not from their Mind, but from their Senses, or from some preconceived Opinion: For we can never doubt of those things which we clearly and distinctly know. As will be evident to those who by frequent Meditation, and earnest Study, have acquir'd a habit of Judging between a clear and dark Conception.
VII. The fore∣said Rule is not to be extended to Believers. We are also to take Notice, that when we assert that to be true which is evidently and distinctly known by us; and therefore that we are not to give our Assent to things that are not so known by us, this is not to be understood of Matters of Faith; forasmuch as they are not accompanied with any such Evidence, neither have we any clear No∣tions of them, as we have of the Subjects of Na∣tural Sciences. For there is a vast difference betwixt the Mysteries of Faith and Natural things, because in these Evidence, but in the former Authority com∣mands our Assent. That a Man may be a Believer, he must believe without Evidence; but to be a Philosopher, he must have a clear and distinct Per∣ception.
VIII. How a man may be cer∣tain that he clearly knows a thing. If any Man demand, How he may be sure of his knowing a thing clearly and distinctly? I answer; If he follow the Order prescribed by right Reason; if he do not precipitate his Judgment, be∣fore he be enlighted with the Truth of Evident Perception. So that the Judgment of our Under∣standing must always go before, as it does when we never assert or deny any thing, except it be of Things we have clearly and distinctly perceived; that is, when our Judgment is exactly conform to our Perception. For it is not a sufficient Argument for us to embrace any Opinion, because there is Truth in it, except the same do appear to us; so as that our Perception may be the Rule and Line of Truth to us.