He who hid well, lived well.

How do we know that anything really exists, that anything is really the way it seems ot us through our senses?

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.

The entire method consists in the order and arrangement of the things to which the mind's eye must turn so that we can discover some truth.

The principal use of prudence, of self-control, is that it teaches us to be masters of our passions, and to so control and guide them that the evils which they cause are quite bearable, and that we even derive joy from them all.

But I cannot forget that, at other times I have been deceived in sleep by similar illusions; and, attentively considering those cases, I perceive so clearly that there exist no certain marks by which the state of waking can ever be distinguished from sleep, that I feel greatly astonished; and in amazement I almost persuade myself that I am now dreaming.

He lives well who is well hidden.