giving us the just Dimensions of all the Parts and Figures, which can enter into any Species of Machine; but still the Discovery of the Law itself is owing merely to Experience, and all the abstract Reasonings in the World could never lead us one Step towards the Knowledge of it. When we reason a priori, and consider merely any Object or Cause, as it appears to the Mind, independent of all Observation, it never could suggest to us the Notion of any distinct Object, such as its Effect; much less, show us the inseparable and inviolable Connexion betwixt them. A Man must be very sagacious, who could discover by Reasoning, that Crystal is the Effect of Heat and Ice of Cold, without being previously acquainted with the Operations of these Qualities.
PART II.
But we have not, as yet, attain'd any tolerable Satisfaction with regard to the Question first propos'd. Each Solution still gives rise to a new Question as difficult as the foregoing, and leads us on to farther Enquiries. When it is ask'd, What is the Nature of all our Reasonings concerning Matter of Fact? the proper Answer seems to be, that they are founded on the Relation of Cause and Effect. When again it is ask'd, What is the Foundation of all our Reasonings and Conclusions concerning that Relation? it may be reply'd in one Word, Experience. But if we still carry onour
