“Doubt is the origin of wisdom”

“Dubium sapientiae initium. (Doubt is the origin of wisdom.)”

“I doubt, therefore I think, therefore I am.”

“The first precept was never to accept a thing as true until I knew it as such without a single doubt.”

“In order to seek truth, it is necessary once in the course of our life to doubt, as far as possible, of all things.”

“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.”

“I am thing that thinks: that is, a things that doubts,affirms, denies, understands a few things, is ignorant of many things, is willing, is unwilling, and also which imagines and has sensory perceptions.”