Give me extension and motion and I will construct the universe.

We call infinite that thing whose limits we have not perceived, and so by that word we do not signify what we understand about a thing, but rather what we do not understand.

Bad books engender bad habits, but bad habits engender good books.

You just keep pushing. You just keep pushing. I made every mistake that could be made. But I just kept pushing.

Let whoever can do so deceive me, he will never bring it about that I am nothing, so long as I continue to think I am something.

Every man is indeed bound to do what he can to promote the good of others, and a man who is of no use to anyone is strictly worthless.

For to be possessed of a vigorous mind is not enough; the prime requisite is rightly to apply it.