Physics, beware of metaphysics.

Poetry is a kind of ingenious nonsense.

God created everything by number, weight and measure.

Sir Isaac Newton was asked how he discovered the law of gravity. He replied, "By thinking about it all the time.

What goes up must come down.

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.

I know not how I seem to others, but to myself I am but a small child wandering upon the vast shores of knowledge, every now and then finding a small bright pebble to content myself with while the vast ocean of undiscovered truth lay before me.