I know that I exist; the question is, What is this 'I' that 'I' know.

An optimist may see a light where there is none, but why must the pessimist always run to blow it out?

Wonder is the first of all the passions.

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.

And thereby make ourselves, as it were, the lords and masters of nature.

It's the familiar love-hate syndrome of seduction: "I don't really care what it is I say, I care only that you like it."

I accept no principles of physics which are not also accepted in mathematics.