( 5«« ) 
THE 
PREFACE. 
SO many and fo large Steps having leen made towards 
the Difcovery of Nature by the indefatigable In- 
duflry of this laft Age, it may feem as if the Sub- 
Jeff were almoft exhaufled, and Nature her felf wearied 
with the Courtfhips of fo many Pretenders : But if o* 
the other fide, we confider the vaff, not to fay boundlel§ 
Extent of the Univerle, and that the Difcovery of one 
Phenomenon leads to, as well as entkes to the Search 
after another ; together with how eafie a thing it is, even 
to impofe on our f elves ground left Opinions inftead of 
Real Knowledge we muft own the Work at leafl great 
enough for the Age of the World, and fooner doubt our 
own Refolutions and Abilities ; than fear the Failure of 
fit Subjects to entertain our Thoughts. 
Real Knowledge is a nice thing ; and as no Man can he 
faid to be Matter of that which he cannot teach to another, 
fo neither can the Mind it felf, at baft as to Phyfical 
matters, le allowed to apprehend that whereof it has not 
in fome fence a Mechanical Conception ; for this 
Knowledge entring wholly by the Senfes , whofe Objefts 
only are Bodies, whereof their Organs have the Percep- 
tion, lut from the Magnitude, Figure, Situation and 
Motion of them, which are all mechanically to be con- 
fider d, or we come fhort of a Satisfactory Information, 
it follows , that Number, Weight and Mcafure muH be 
A z & lyed 
