I think; therefore I am.

To live without philosophizing is in truth the same as keeping the eyes closed without attempting to open them.

I am indeed amazed when I consider how weak my mind is and how prone to error.

Bad books engender bad habits, but bad habits engender good books.

If I go for the alternative which is false, then obviously I shall be in error; if I take the other side, then it is by... chance that I arrive at the truth, and I shall still be at fault.... In this incorrect use of free will may be found the privation which constitutes the essence of error.

Few look for truth; many prowl about for a reputation of profundity by arrogantly challenging whichever arguments are the best.

...it is certain that I am really distinct from my body, and can exist without it.