1. “Archimedes, in order that he might draw the terrestrial globe out of its place . . . demanded only that one point should be fixed and immovable, in the same way I shall have . . . high hopes if I . . . discover one thing only which is certain and indubitable.”
2. “[Body] is by nature always divisible, and the mind is entirely indivisible.”
3. “Divide each difficulty into as many parts as is feasible and necessary to resolve it.”
4. “Each substance has a principal attribute, and . . . the attribute of the mind is thought, while that of body is extension.”
5. “Each problem that I solved became a rule which served afterwards to solve other problems.”
6. “Everybody thinks himself so well supplied with common sense that even those most difficult to please… never desire more of it than they already have.”
7. “Except our own thoughts, there is nothing absolutely in our power.”
8. “I am accustomed to sleep and in my dreams to imagine the same things that lunatics imagine when awake.”
9. “"I am, I exist" is necessarily true each time that I pronounce it, or that I mentally conceive it.”
10. ”If you would be a real seeker after truth, you must at least once in your life doubt, as far as possible, all things.”
11. ”I hope that posterity will judge me kindly, not only as to the things which I have explained, but also to those which I have intentionally omitted so as to leave to others the pleasure of discovery.”
12. “I see so manifestly that there are no certain indications by which we may clearly distinguish wakefulness from sleep.”
13. “I shall then suppose . . . some evil genius not less powerful than deceitful, has employed his whole energies in deceiving me; I shall consider that . . . all . . . external things are but illusions and dreams of which this genius has availed himself to lay traps for my credulity.”
14. ”It is not enough to have a good mind. The main thing is to use it well.”
15. “It's the heart afraid of breaking that never learns to dance. It is the dream afraid of waking that never takes the chance. It is the one who won't be taken who cannot seem to give. And the soul afraid of dying that never learns to live.”
16. “It is well to know something of the manners of various peoples, in order more sanely to judge our own, and that we do not think that everything against our modes is ridiculous, and against reason, as those who have seen nothing are accustomed to think.”
17. “I will suppose that… some malicious demon of the utmost power and cunning has employed all his energies in order to deceive me. I shall think that the sky, the air, the earth, colours, shapesm sounds and all external things are merely the delusions of dreams which he has devised to ensnare my judgement. I shall consider myself as not having hands or eyes, or flesh, or blood or senses, but as falsely believing that I have all these things.”
18. “Nature also teaches me by the sensations of pain, hunger, thirst, etc. that I am not only lodged in my body as a pilot in a vessel, but that I am very closely united to it, and so to speak so intermingled with it that I seem to compose with it one whole.”
19. ”One cannot conceive anything so strange and so implausible that it has not already been said by one philosopher or another.”
20. “ [O]wing to the fact that the destruction of the foundations of necessity brings with it the downfall of the rest of the edifice, I shall only in the first place attack those principles upon which all my former opinions rested.”
21. ”Perfect numbers like perfect men are very rare.”
22. “The first precept was never to accept a thing as true until I knew it as such without a single doubt.”
23. “[T]he principal error and the commonest which we may meet with in them, consists in my judging that the ideas which are in me are similar or conformable to the things which are outside me . . . .”
24. “[Thought] alone cannot be separated from me.”
25. “To know what people really think, pay regard to what they do, rather than what they say.”
26. “Traveling is almost like talking with men of other centuries.”
27. “What is a thing which thinks? It is a thing which doubts, understands, [conceives], affirms, denies, wills, refuses, which also imagines and feels.”
28. “Whenever anyone has offended me, I try to raise my soul so high that the offense cannot reach it.”
29. “When I consider this carefully, I find not a single property which with certainty separates the waking state from the dream. How can you be certain that your whole life is not a dream?”
30. “When writing about transcendental issues, be transcendentally clear.”
