The ancients divided mechanics into two parts: the rational, which proceeds rigorously through demonstrations, and the practical. Practical mechanics is the subject that comprises all the manual artist, form which the subject of mechanics as a whole has adopted its name, from which the subject of mechanics as a whole has adopted its name. But since those who practice an art do not generally work with a high degree of exactness, the whole subject of mechanics is distinguished from geometry by the attribution of exactness to geometry and of anything less than exactness to mechanics.

For the basic problem [lit. whole difficulty] of philosophy seems to be to discover the forces of nature from the phenomena of motions and then to demonstrate the other phenomena from these forces.

Newton, The Principia