It is not enough to have a good mind. The main thing is to use it well. - René Descartes

it
would be surprising if I had a clearer grasp of things that I
realize are doubtful, unknown and foreign to me — ·namely,
bodies· — than I have of what is true and known — namely
my own self. But I see what the trouble is: I keep drifting
towards that error because my mind likes to wander freely,
refusing to respect the boundaries that truth lays down. Very
well, then; I shall let it run free for a while, so that when
the time comes to rein it in it won’t be so resistant to being
pulled back.

engaging in conversation with the most cultivated minds of past centuries who had composed them, or rather, taking part in a well-conducted dialogue in which such minds reveal to us only the best of their thoughts;

I couldn’t exist with the nature that I have – that is, containing within me the idea of God – if God didn’t really exist. By ‘God’ I mean the very being the idea of whom is within me – the one that has no defects and has all those perfections that I can’t grasp but can somehow touch with my thought. This shows clearly that it is not possible for him to be a deceiver, since the natural light makes it clear that all fraud and deception depend on some defect.