#reason

“Rules and formulas, those mechanical aids to the use of reason, are the shackles of a permanent immaturity. What is Enlightenment? (1784)”

“Science is organized knowledge. Wisdom is organized life”

“Enlightenment is man's emergence from his self-incurred immaturity. What is Enlightenment? (1784)”

“Morality is not the doctrine of how we may make ourselves happy, but of how we may make ourselves worthy of happiness. Critique of Practical Reason (1788)”

“Live your life as though your every act were to become a universal law”

“All our knowledge begins with the senses, proceeds then to the understanding, and ends with reason. There is nothing higher than reason. Critique of Pure Reason (1781)”

“Act in such a way that you treat humanity, whether in your own person or in the person of any other, never merely as a means to an end, but always at the same time as an end. Groundwork of the Metaphysics of Morals (1785)”

“Experience without theory is blind, but theory without experience is mere intellectual play”

“Two things fill the mind with ever new and increasing admiration and reverence, the more often and more steadily one reflects on them: the starry heavens above me and the moral law within me. Critique of Practical Reason (1788), Conclusion”

“Have the courage to use your own reason”

“The greatest minds are capable of the greatest vices as well as the greatest virtues. Discourse on the Method (1637), Part I”

“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. Meditations on First Philosophy (1641)”

“The senses deceive from time to time, and it is prudent never to trust wholly those who have deceived us even once. Meditations on First Philosophy (1641), Meditation I”

“When someone says "I think, therefore I am," the term "therefore" does not denote a logical conclusion from a syllogism, but a simple intuition of the mind. Letter to Clerselier (1646)”

“I am accustomed to sleep and in my dreams to imagine the same things that lunatics imagine when awake. Meditations on First Philosophy (1641), Meditation I”

“The reading of all good books is like a conversation with the finest minds of past centuries. Discourse on the Method (1637), Part I”

“Divide each difficulty into as many parts as is feasible and necessary to resolve it. Discourse on the Method (1637), Part II”

“It is not enough to have a good mind; the main thing is to use it well. Discourse on the Method (1637), Part I”

“I doubt, therefore I think; I think, therefore I am. Principles of Philosophy (1644)”

“Cogito ergo sum. I think, therefore I am. Discourse on the Method (1637), Part IV”

“Now as we call every thing custom , which proceeds from a past repetition, without any new reasoning or conclusion, we may establish it as a certain truth, that all the belief, which follows upon any present impression, is deriv'd solely from that origin. Part 3, Section 8”

“We must therefore glean up our experiments in this science from a cautious observation of human life, and take them as they appear in the common course of the world, by men's behaviour in company, in affairs, and in their pleasures. Where experiments of this kind are judiciously collected and compared, we may hope to establish on them a science, which will not be inferior in certainty, and will be much superior in utility to any other of human comprehension. Introduction”

“Here am I who have written on all sorts of subjects calculated to excite hostility, moral, political, and religious, and yet I have no enemies”

“With regard to politics and the character of princes and great men, I think I am very moderate. My views of things are more conformable to Whig principles; my representation of persons to Tory prejudices. Nothing can so much prove that men commonly regard more persons than things, as to find that I am commonly numbered among the Tories. E. C. Mossner, Life of David Hume (Clarendon Press, 2001), p. 311.”

“The conclusion [of the essay 'Of the Protestant Succession'] shows me a Whig, but a very sceptical one. Letter to Henry Home (9 February 1748), quoted in J. Y. T. Greig, The Letters of David Hume: Volume I (Oxford: Clarendon Press, 1932), p. 111”

“Heaven and Hell suppose two distinct species of men, the good and the bad; but the greatest part of mankind float betwixt vice and virtue.”

“As to the Approbation or Esteem of those Blockheads who call themselves the Public, & whom a Bookseller, a Lord, a Priest, or a Party can guide, I do most heartily despise it. Letter 138, To Gilbert Elliot of Minto; August 9, 1757”

“The life of man is of no greater importance to the universe than that of an oyster. On Suicide”

“Does a man of sense run after every silly tale of hobgoblins or fairies, and canvass particularly the evidence ? I never knew anyone, that examined and deliberated about nonsense who did not believe it before the end of his enquiries. Letters”

“The Theory of Moral Sentiments”

“The ordinary surroundings of life which are esteemed by men (as their actions testify) to be the highest good, may be classed under the three heads”

“After experience had taught me that all the usual surroundings of social life are vain and futile; seeing that none of the objects of my fears contained in themselves anything either good or bad, except in so far as the mind is affected by them, I finally resolved to inquire whether there might be some real good having power to communicate itself, which would affect the mind singly, to the exclusion of all else: whether, in fact, there might be anything of which the discovery and attainment would enable me to enjoy continuous, supreme, and unending happiness. I, 1”

“All the better; they do not force me to do anything that I would not have done of my own accord if I did not dread scandal. But since they want it that way, I enter gladly on the path that is opened to me, with the consolation that my departure will be more innocent than was the exodus of the early Hebrews from Egypt. Statement after his excommunication from Jewish society, attributed by Lucas, in The Oldest Biography of Spinoza (1970) by A. Wolf; also in Spinoza: A Life (1999) by Steven Nadler”

“Of all the things that are beyond my power, I value nothing more highly than to be allowed the honor of entering into bonds of friendship with people who sincerely love truth . For, of things beyond our power, I believe there is nothing in the world which we can love with tranquility except such men. Spinoza, Correspondence, 146, Letter xix”

“Nature is satisfied with little; and if she is, I am also. As quoted in The Story of Philosophy (1933) by Will Durant , p. 176”

“How I know that my philosophy is the best among all that have ever been taught in the world, or are being taught, or ever will be taught?”

“I make this chief distinction between religion and superstition , that the latter is founded on ignorance, the former on knowledge ; this, I take it, is the reason why Christians are distinguished from the rest of the world, not by faith , nor by charity , nor by the other fruits of the Holy Spirit, but solely by their opinions, inasmuch as they defend their cause, like everyone else, by miracles, that is by ignorance , which is the source of all malice; thus they turn a faith, which may be true, into superstition. Letter 21 (73) to Henry Oldenburg , November”

“If I had as clear an idea of ghosts, as I have of a triangle or a circle, I should not in the least hesitate to affirm that they had been created by God; but as the idea I possess of them is just like the ideas, which my imagination forms of harpies, gryphons, hydras, &c., I cannot consider them as anything but dreams, which differ from God as totally as that which is not differs from that which is. Letter to Hugo Boxel (October 1674) The Chief Works of Benedict de Spinoza (1891) Tr. R. H. M. Elwes, Vol. 2, Letter 58 (54).”

“This I know, that between finite and infinite there is no comparison; so that the difference between God and the greatest and most excellent created thing is no less than the difference between God and the least created thing. Letter to Hugo Boxel (October 1674) The Chief Works of Benedict de Spinoza (1891) Tr. R. H. M. Elwes, Vol. 2, Letter 58 (54).”

“Principles of Descartes”