Euclid, would for ever retain all their Truth and Evidence.
Matters of Fact, which are the second Objects of human Reason, are not ascertain'd to us in the same Manner; nor is our Evidence of their Truth, however great, of a like Nature with the foregoing. The contrary of every Matter of Fact is still possible; because it can never imply a Contradiction, and is conceiv'd by the Mind with equal Distinctness and Facility, as if ever so conformable to Truth and Reality. That the Sun will not rise To-morrow is no less intelligible a Proposition, and implies no more Contradiction, than the Affirmation, that it will rise. We should in vain, therefore, attempt to demonstrate its Falshood. Were it demonstratively false, it would imply a Contradiction, and could never be distinctly conceiv'd by the Mind.
It may, therefore, be a Subject, worthy Curiosity, to enquire what is the Nature of that Evidence, which assures us of any real Existence and Matter of Fact, beyond the present Testimony of our Senses, or the Records of our Memory. This Part of Philosophy, 'tis observable, has been little cultivated, either by the Antients or Moderns; and therefore our Doubts and Errors, in the Prosecution of so important an Enquiry, may be the more excusable, while we marchthro
