The only thing we have power over in the universe is our own thoughts.

In the matter of a difficult question it is more likely that the truth should have been discovered by the few than by the many.

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

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."

Your joy is your sorrow unmasked. And the self-same well from which your laughter rises was often-times filled with your tears.

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.

Even the mind depends so much on temperament and the disposition of one's bodily organs that, if it is possible to find a way to make people generally more wise and more skilful than they have been in the past, I believe that we should look for it in medicine. It is true that medicine as it is currently practiced contains little of much use.