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.

To myself I am only a child playing on the beach, while vast oceans of truth lie undiscovered before me

A body in motion tends to stay in motion unless acted on by an outside force.

Are not gross bodies and light convertible into one another; and may not bodies receive much of their activity from the particles of light which enter into their composition? The changing of bodies into light, and light into bodies, is very conformable to the course of Nature, which seems delighted with transmutations.

To every action there is always opposed an equal reaction.

Did blind chance know that there was light and what was its refraction, and fit the eyes of all creatures after the most curious manner to make use of it? These and other suchlike considerations, always have, and always will prevail with mankind, to believe that there is a Being who made all things, who has all things in his power, and who is therefore to be feared.

In the absence of any other proof, the thumb alone would convince me of God's existence.