French philosopher, mathematician, and scientist (1596-1650)
- "Dubium sapientiae initium."
- English: Doubt is the origin of wisdom.
- What it means: When you have doubt you become wiser.
- "Cogito, ergo sum."
- English: I think, therefore I am.
- What it means: You exist because you think.
- "Ex nihilo nihil fit."
- English: Nothing comes out of nothing.
- What it means: If you do not do anything, nothing happens.