INTRODUCTION.

inquiry cannot properly have place in the deliberation about ad-mitting any property of matter or bodies into philofophy; forthat purpofo it is only to be confidered, whether the exiftenceof fuch a property has been juftly proved or not. Thereforeto decide what caufes of things are rightly received into na-tural philofophy, requires only a diftinCt and clear conception;,of what kind of reafoning is to be allowed of as convincing,,when we argue upon the works of nature..

10. The proofs in natural philofophy cannot be fo abfo-lutely conclufive, as i ;the mathematics. For the fubjects ofthat fcience are purely' the ideas of our own minds.- They’may be reprefented to our fenfes by material objects, but theyare themfelves the arbitrary productions of our own thoughts ;fo that as the mind can have a full and adequate knowledge’of its own ideas, the reafoning in geometry can be renderedperfect. But in natural knowledge the fubjeCt of our con-templation is without us, and not fo compleatly to be known:’therefore our method of arguing muft fall a little fhortof ah~folute,perfection. It is only here required to fleer a juft courfebetween the conjectural method of proceeding, againft which?I have fo largely fpoke; and demanding fo rigorous a proof, aswill reduce all philofophy to mere foepticifm, and exclude all'profpeCt of making any progrefs in the knowledge of "nature..

2.1. The conceffions, which are to be allowed in this fci-ence, ’ are by Sir Isaac Newton included under a very-'few fimple precepts.. •

xi. The