Postulates.

1st. I request that my readers consider how feeble are the reasons that have hitherto led them to repose faith in their senses, and how uncertain arc all the judgments which they afterward founded on them; and that they will revolve this consideration in their mind so long and so frequently, that, in fine, they may acquire the habit of no longer trusting so confidently in their senses; for I hold that this is necessary to render one capable of apprehending metaphysical truths.

2d. That they consider their own mind, and all those of its attributes of which they shall find they cannot doubt, though they may have supposed that all they ever received by the senses was entirely false, and that they do not leave off considering it until they have acquired the habit of conceiving it distinctly, and of believing that it is more easy to know than any corporeal object.

3d. That they diligently examine such propositions as are self-evident, which they will find within themselves, as the following: That the same thing cannot at once be and not be; that nothing cannot be the efficient cause of anything, and the like; and thus exercise that clearness of understanding that has been given them by nature, but which the perceptions of the senses are wont greatly to disturb and obscure — exercise it, I say, pure and delivered from the objects of sense; for in this way the truth of the following axioms will appear very evident to them.

4th. That they examine the ideas of those natures which contain in them an assemblage of several attributes, such as the nature of the triangle, that of the square, or some other figure; as also the nature of mind, the nature of body, and above all that of God, or of a being supremely perfect. And I request them to observe that it may with truth be affirmed that all these things are in objects, which we clearly conceive to be contained in them: for example, because that, in the nature of the rectilineal triangle, this property is found contained — viz., that its three angles are equal to two right angles, and that in the nature of body or of an extended thing, divisibility is comprised (for we do not conceive any extended thing so small that we cannot divide it, at least in thought)—it is true that the three angles of a rectilineal triangle are equal to two right angles, and that all body is divisible.

5th. That they dwell much and long on the contemplation of the supremely perfect Being, and, among other things, consider that in the ideas of all other natures, possible existence is indeed contained, but that in the idea of God is contained not only possible but absolutely necessary existence. For, from this alone, and without any reasoning, they will discover that God exists: and it will be no less evident in itself than that two is an equal and three an unequal number, with other truths of this sort. For there are certain truths that are thus manifest to some without proof, which are not comprehended by others without a process of reasoning.

6th. That carefully considering all the examples of clear and distinct perception, and all of obscure and confused, of which I spoke in my Meditations, they accustom themselves to distinguish things that are clearly known from those that are obscure, for this is better learned by example than by rules; and I think that I have there opened up, or at least in some degree touched upon, all examples of this kind.

7th. That readers adverting to the circumstance that they never discovered any falsity in things which they clearly conceived, and that, on the contrary, they never found, unless by chance, any truth in things which they conceived but obscurely, consider it to be wholly irrational, if on account only of certain prejudices of the senses, or hypotheses which contain what is unknown, they call in doubt what is clearly and distinctly conceived by the pure understanding; for they will thus readily admit the following axioms to be true and indubitable, though I confess that several of them might have been much better unfolded, and ought rather to have been proposed as theorems than as axioms, if I had desired to be more exact.