I have presented principles of philosophy that are not, however, philosophical but strictly mathematical-that is, those on which the study of philosophy can be based. These principles are the laws and conditions of motions and of forces, which especially relate to philosophy.

Do not the Rays which differ in Refrangibility differ also in Flexibity; and are they not by their different Inflexions separated from one another, so as after separation to make the Colours in the three Fringes above described? And after what manner are they inflected to make those Fringes?

Every action has an equal and opposite reaction

When two forces unite, their efficiency double.

. . . Newton was an unquestioning believer in an all-wise creator of the universe, and in his own inability - like the boy on the seashore - to fathom the entire ocean in all its depths. He therefore believed that there were not only many things in heaven beyond his philosophy, but plenty on earth as well, and he made it his business to understand for himself what the majority of intelligent men of his time accepted without dispute (to them it was as natural as common sense) - the traditional account of the creation.

To explain all nature is too difficult a task for any one man or even for any one age. Tis much better to do a little with certainty & leave the rest for others that come after than to explain all things by conjecture without making sure of any thing.

Absolute, true and mathematical time, of itself, and from its own nature flows equably without relation to anything external.