I should consider that I know nothing about physics if I were able to explain only how things might be, and were unable to demonstrate that they could not be otherwise.

I have concluded the evident existence of God, and that my existence depends entirely on God in all the moments of my life, that I do not think that the human spirit may know anything with greater evidence and certitude.

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."

The principal effect of the passions is that they incite and persuade the mind to will the events for which they prepared the body.

On the one hand I have a clear and distinct idea of myself, in so far as I am a thinking, non-extended thing; and on the other hand I have a distinct idea of body, in so far a this is simply an extended, non-thinking thing. And, accordingly, it is certain that I am really distinct from my body, and exist without it.

We never understand a thing so well,and make it our own, as when we have discovered it for ourselves.

There is nothing so strange and so unbelievable that it has not been said by one philosopher or another.