To derive two or three general Principles of Motion from Phænomena, and afterwards to tell us how the Properties and Actions of all corporeal Things follow from those manifest Principles, would be a very great step in Philosophy.

Every body persists in a state of rest or of uniform motion in a straight line, unless it is compelled to change that state by forces having impact upon it.

No great discovery was ever made without a bold guess.

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.

Plato is my friend, Aristotle is my friend, but my greatest friend is truth.

A man may imagine things that are false, but he can only understand things that are true, for if the things be false, the apprehension of them is not understanding.

Against filling the Heavens with fluid Mediums, unless they be exceeding rare, a great Objection arises from the regular and very lasting Motions of the Planets and Comets in all manner of Courses through the Heavens.