"Having thus assumed the motions which I ascribe to the earth, I have, after long and careful investigation, finally discovered that, if the motions of the other planets be related to the revolution of…"

"The Universe has been wrought for us by a supremely good and orderly Creator."

"Nor do I doubt that learned and skillful mathematicians will agree with me if they are willing to give not superficial but profound attention to the arguments I adduce in this work."

"For it is not necessary that hypotheses should be true, or even probable; it is enough if they provide a calculus which agrees with the observations."

"Those things which I am saying now may be obscure, yet they will be made clearer in their proper place."