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.

In God there is an infinitude of things which I cannot comprehend, nor possibly even reach in any way by thought; for it is the nature of the infinite that my nature, which is finite and limited, should not comprehend it.

When writing about transcendental issues, be transcendentally clear.

Situations in life often permit no delay; and when we cannot determine the course which is certainly best, we must follow the one which is probably the best. This frame of mind freed me also from the repentance and remorse commonly felt by those vacillating individuals who are always seeking as worthwhile things which they later judge to be bad.

Divide each difficulty into as many parts as is feasible and necessary to resolve it.

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.

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