Our present work sets forth mathematical principles of philosophy. For the basic problem 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. It is to these ends that the general propositions in books 1 and 2 are directed, while in book 3 our explanation of the system of the world illustrates these propositions.

The Synthesis consists in assuming the Causes discovered and established as Principles, and by them explaining the Phænomena proceeding from them, and proving the Explanations.

His epitaph: Who, by vigor of mind almost divine, the motions and figures of the planets, the paths of comets, and the tides of the seas first demonstrated.

Whence arises all that order and beauty we see in the world?

Truth is the offspring of silence and meditation.

Hypotheses non fingo. I frame no hypotheses.

The way to chastity is not to struggle directly with incontinent thoughts but to avert the thoughts by some imployment, or by reading, or meditating on other things.