BY SIR ISAAC NEWTON.

(1686)[A] Since the ancients (as we are told by Pappus) made great account of the science of mechanics in the investigation of natural things; and the moderns, laying aside substantial forms and occult qualities, have endeavored to subject the phenomena of nature to the laws of mathematics, I have in this treatise cultivated mathematics so far as it regards philosophy.

The ancients considered mechanics in a twofold respect; as rational, which proceeds accurately by demonstration, and practical.

To practical mechanics all the manual arts belong, from which mechanics took its name.

But as artificers do not work with perfect accuracy, it comes to pass that mechanics is so distinguished from geometry, that what is perfectly accurate is called geometrical; what is less so is called mechanical.