It is not enough to have a good mind; the main thing is to use it well.
Divide each difficulty into as many parts as is feasible and necessary to resolve it.
If you would be a real seeker after truth, it is necessary that at least once in your life you doubt, as far as possible, all things.
The senses deceive from time to time, and it is prudent never to trust wholly those who have deceived us even once.
