As astronomy is the daughter of idleness, geometry is the daughter of property.

Let us be well assured of the Matter of Fact, before we trouble our selves with enquiring into the Cause. It is true, that this Method is too slow for the greatest part of Mankind, who run naturally to the Cause, and pass over the Truth of the Matter of Fact.

Nature is never so admired as when she is understood.

Since the princes take the Earth for their own, it's fair that the philosophers reserve the sky for themselves and rule there, but they should never permit the entry of others.

They will have the World to be in Large, what a Watch is in Small; which is very regular, and depends only upon the just disposing of the several Parts of the Movement.

To what purpose should People become fond of the Mathematicks and Natural Philosophy? ... People very readily call Useless what they do not understand. It is a sort of Revenge... One would think at first that if the Mathematicks were to be confin'd to what is useful in them, they ought only to be improv'd in those things which have an immediate and sensible Affinity with Arts, and the rest ought to be neglected as a Vain Theory. But this would be a very wrong Notion. As for Instance, the Art of Navigation hath a necessary Connection with Astronomy, and Astronomy can never be too much improv'd for the Benefit of Navigation. Astronomy cannot be without Optics by reason of Perspective Glasses: and both, as all parts of the Mathematicks are grounded upon Geometry ... .

You say Beasts are Machines like Watches? But put the Machine called a Dog, and the Machine called a Bitch to one another for some time, and there may result another little Machine; whereas two Watches might be together all their Life-time, without ever producing a third Watch. Now Madam de B— and I think, according to our Philosophy, that all things which being but two, are endued with the Virtue of making themselves three, are of a much higher Nature than a Machine.