To arrive at the simplest truth requires years of contemplation.
I shall not mingle conjectures with certainties.
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.
I do not feign hypotheses.
There are more sure marks of authenticity in the Bible than in any profane history.
I keep the subject of my inquiry constantly before me, and wait till the first dawning opens gradually, by little and little, into a full and clear light.