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ESSAY IV.
Sceptical Doubts concerning the Operations of the Understanding.
PART I.
All the Objects of human Reason or Enquiry may naturally be divided into two Kinds, viz. Relations of Ideas and Matters of Fact. Of the first Kind are the Propositions in Geometry, Algebra, and Arithmetic; and in short, every Proposition, that is either intuitively or demonstratively certain. That the Square of the Hypothenuse is equal to the Squares of the two Sides, is a Proposition, that expresses a Relation betwixt these Figures. That three times five is equal to the half of thirty, expresses a Relation betwixt these Numbers. Propositions of this Kind are discoverable by the mere Operation of Thought, without Dependance on what is any where existent in the Universe. Tho' there never were a true Circle or Triangle in Nature, the Propositions, demonstrated byEuclid,
