If two angels were sent down from heaven -one to conduct an empire and the other to sweep the streets -they would feel no inclination to change employment because an angel would know that no matter what we are doing, it's an opportunity to bring joy, deepen our understanding and expand our life.

My Design in this Book is not to explain the Properties of Light by Hypotheses, but to propose and prove them by Reason and Experiments: In order to which, I shall premise the following Definitions and Axioms.

As a blind man has no idea of colors, so we have no idea of the manner by which the all-wise God perceives and understands all things.

To explain all nature is too difficult a task for any one man or even for any one age

What we know is a drop, what we don't know is an ocean.

Do not Bodies and Light act mutually upon one another; that is to say, Bodies upon Light in emitting, reflecting, refracting and inflecting it, and Light upon Bodies for heating them, and putting their parts into a vibrating motion wherein heat consists?

He who thinks half-heartedly will not believe in God; but he who really thinks has to believe in God.