--- title: "Meaning & Key Takeaway of: But I cannot forget that, at other times…" description: "\"But I cannot forget that, at other times I have been deceived in sleep by similar illusions; and, attentively considering those cases, I perceive so cl..." image: "https://sms4smile.com/quotes/i/97f/ren-descartes-1376_amazement_but-i-cannot-forget-that-at-other-times_2028874.png" --- # But I cannot forget that, at other times I have been… ![“But I cannot forget that, at other times I have been deceived in sleep by similar illusions; and, attentively considering those cases, I perceive so clearly that there exist no certain marks by which the state of waking can ever be distinguished from sleep, that I feel greatly astonished; and in…” quote by Rene Descartes](https://sms4smile.com/quotes/i/97f/ren-descartes-1376_amazement_but-i-cannot-forget-that-at-other-times_2028874.png) [Download](https://sms4smile.com/quotes/i/97f/ren-descartes-1376_amazement_but-i-cannot-forget-that-at-other-times_2028874.png) [Open image](https://sms4smile.com/quotes/i/97f/ren-descartes-1376_amazement_but-i-cannot-forget-that-at-other-times_2028874.png) > “But I cannot forget that, at other times I have been deceived in sleep by similar illusions; and, attentively considering those cases, I perceive so clearly that there exist no certain marks by which the state of waking can ever be distinguished from sleep, that I feel greatly astonished; and in amazement I almost persuade myself that I am now dreaming.” [Rene Descartes](https://sms4smile.com/quotes/author/ren-descartes/) ## About This Quote This interpretation was drafted with AI assistance. It is one reading of the quote, not the author's own explanation. Descartes doubts the reliability of sensory experience, suggesting waking and dreaming may be indistinguishable. **In simple terms:** We cannot trust our senses to tell reality from illusion. Key Takeaway Question reality, seek evidence beyond perception. Themes philosophy epistemology reality mind illusion Mood curious skeptical Type philosophical reflective When to use this quote - personal introspection - philosophical debate - psychology research - dream analysis Key Concepts Cartesian doubt consciousness perception skepticism Questions to Reflect On - How do you verify what is real? - What evidence do you need to trust a perception? A Different Perspective Dreams can be vivid and convincing, challenging certainty. ★ ★ ★ ★ ★ No ratings yet [Amazement](https://sms4smile.com/quotes/about/amazement/) [Cases](https://sms4smile.com/quotes/about/cases/) [Certain](https://sms4smile.com/quotes/about/certain/) [Considering](https://sms4smile.com/quotes/about/considering/) [Deceived](https://sms4smile.com/quotes/about/deceived/) [Deceived Sleep](https://sms4smile.com/quotes/about/deceived-sleep-3714934/) [Distinguished](https://sms4smile.com/quotes/about/distinguished/) [Dream](https://sms4smile.com/quotes/about/dream/) [Dreaming](https://sms4smile.com/quotes/about/dreaming/) [Feels](https://sms4smile.com/quotes/about/feels/) [Forget](https://sms4smile.com/quotes/about/forget/) [Illusion](https://sms4smile.com/quotes/about/illusion/) [Illusions Attentively](https://sms4smile.com/quotes/about/illusions-attentively-3714936/) [Mark](https://sms4smile.com/quotes/about/mark/) [Perceive](https://sms4smile.com/quotes/about/perceive/) [Similar Illusions](https://sms4smile.com/quotes/about/similar-illusions-3714937/) [Sleep](https://sms4smile.com/quotes/about/sleep/) [States](https://sms4smile.com/quotes/about/states/) [Waking](https://sms4smile.com/quotes/about/waking/) [Waking Distinguished](https://sms4smile.com/quotes/about/waking-distinguished-3714935/) ## Related quotes > [“I suppose therefore that all things I see are illusions; I believe that nothing has ever existed of everything my lying memory tells me.…](https://sms4smile.com/quotes/ren-descartes/i-suppose-therefore-that-all-things-i-see-are-illusions-i-believe/) [René Descartes](https://sms4smile.com/quotes/author/ren-descartes/) > [In philosophy, when we make use of false principles, we depart the farther from the knowledge of truth and wisdom exactly in proportion to…](https://sms4smile.com/quotes/ren-descartes/in-philosophy-when-we-make-use-of-false-principles-we-depart-the/) [Rene Descartes](https://sms4smile.com/quotes/author/ren-descartes/) > [Ten times a day something happens to me like this - some strengthening throb of amazement - some good sweet empathic ping and swell.…](https://sms4smile.com/quotes/mary-oliver/ten-times-a-day-something-happens-to-me-like-this-some-strengthening/) [Mary Oliver](https://sms4smile.com/quotes/author/mary-oliver/) > [Basically, I want to spend my time in retreat, but to my own amazement, I agreed to help with a project to start a…](https://sms4smile.com/quotes/tenzin-palmo/basically-i-want-to-spend-my-time-in-retreat-but-to-my-own-amazement/) [Tenzin Palmo](https://sms4smile.com/quotes/author/tenzin-palmo/) > [I realized a long time ago, with a certain amazement, that no mattter how important something is in your life, no matter how huge…](https://sms4smile.com/quotes/sharon-shinn/i-realized-a-long-time-ago-with-a-certain-amazement-that-no-mattter/) [Sharon Shinn](https://sms4smile.com/quotes/author/sharon-shinn/) > [Adlai Stevenson, himself a notable speaker, often reminisced about his last meeting with Churchill. I asked him on whom or what he had based…](https://sms4smile.com/quotes/william-bourke-cockran/adlai-stevenson-himself-a-notable-speaker-often-reminisced-about-his/) [William Bourke Cockran](https://sms4smile.com/quotes/author/william-bourke-cockran/) > [Other people's marriages are a perpetual source of amazement.](https://sms4smile.com/quotes/patrick-o-brian/other-people-s-marriages-are-a-perpetual-source-of-amazement/) [Patrick O'Brian](https://sms4smile.com/quotes/author/patrick-o-brian/) > [When one thinks of the wondrous glory of Christ, how astonishing that He can join with us! But more, when one thinks of His…](https://sms4smile.com/quotes/george-wigram/when-one-thinks-of-the-wondrous-glory-of-christ-how-astonishing-that/) [George Wigram](https://sms4smile.com/quotes/author/george-wigram/) > [Sometime in the last ten years the best brains of the Occident discovered to their amazement that we live in an Environment. This discovery…](https://sms4smile.com/quotes/gary-snyder/sometime-in-the-last-ten-years-the-best-brains-of-the-occident/) [Gary Snyder](https://sms4smile.com/quotes/author/gary-snyder/) > [He sees with amazement that our defeats are but the stepping stones to victory and that all his victories are stepping stones to ruin.…](https://sms4smile.com/quotes/winston-churchill/he-sees-with-amazement-that-our-defeats-are-but-the-stepping-stones/) [Winston Churchill](https://sms4smile.com/quotes/author/winston-churchill/) > [I think it wasn't so much that the White House altered me in any essential way as that I found the resources with which…](https://sms4smile.com/quotes/betty-ford/i-think-it-wasn-t-so-much-that-the-white-house-altered-me-in-any/) [Betty Ford](https://sms4smile.com/quotes/author/betty-ford/) > [The very fact that we make such a to-do over golden weddings indicates our amazement at human endurance. The celebration is more in the…](https://sms4smile.com/quotes/ilka-chase/the-very-fact-that-we-make-such-a-to-do-over-golden-weddings/) [Ilka Chase](https://sms4smile.com/quotes/author/ilka-chase/) > [With education symmetrical and true we will take the dead mass buried by slavery's hand and touch them to life. This beauteous angel, which…](https://sms4smile.com/quotes/william-tecumseh-vernon/with-education-symmetrical-and-true-we-will-take-the-dead-mass-buried/) [William Tecumseh Vernon](https://sms4smile.com/quotes/author/william-tecumseh-vernon/) > [When I got on the set of 'Saving Private Ryan,' I discovered, to my amazement, that Steven Spielberg is a gamer.](https://sms4smile.com/quotes/vin-diesel/when-i-got-on-the-set-of-saving-private-ryan-i-discovered-to-my/) [Vin Diesel](https://sms4smile.com/quotes/author/vin-diesel/) > [We started this together, Leo. Seems only right you come along. You find us a ride, you're in." "Yes!" Leo pumped his fist. \*…](https://sms4smile.com/quotes/rick-riordan/we-started-this-together-leo-seems-only-right-you-come-along-you-find/) [Rick Riordan](https://sms4smile.com/quotes/author/rick-riordan/) ## More by Rene Descartes > [“My third maxim was to endeavour always to conquer myself rather than fortune, and change my desires rather than the order of the world,…](https://sms4smile.com/quotes/ren-descartes/my-third-maxim-was-to-endeavour-always-to-conquer-myself-rather-than/) [René Descartes](https://sms4smile.com/quotes/author/ren-descartes/) > [Your joy is your sorrow unmasked. And the self-same well from which your laughter rises was often-times filled with your tears.](https://sms4smile.com/quotes/ren-descartes/your-joy-is-your-sorrow-unmasked-and-the-self-same-well-from-which/) [Rene Descartes](https://sms4smile.com/quotes/author/ren-descartes/) > [So blind is the curiosity by which mortals are possessed, that they often conduct their minds along unexplored routes, having no reason to hope…](https://sms4smile.com/quotes/ren-descartes/so-blind-is-the-curiosity-by-which-mortals-are-possessed-that-they/) [Rene Descartes](https://sms4smile.com/quotes/author/ren-descartes/) > [“For to be possessed of a vigorous mind is not enough; the prime requisite is rightly to apply it. The greatest minds, as they…](https://sms4smile.com/quotes/ren-descartes/for-to-be-possessed-of-a-vigorous-mind-is-not-enough-the-prime/) [René Descartes](https://sms4smile.com/quotes/author/ren-descartes/) > [“It is useful to know something of the manners of different nations, that we may be enabled to form a more correct judgment regarding…](https://sms4smile.com/quotes/ren-descartes/it-is-useful-to-know-something-of-the-manners-of-different-nations/) [René Descartes](https://sms4smile.com/quotes/author/ren-descartes/) > [A state is better governed which has few laws, and those laws strictly observed.](https://sms4smile.com/quotes/ren-descartes/a-state-is-better-governed-which-has-few-laws-and-those-laws-strictly/) [Rene Descartes](https://sms4smile.com/quotes/author/ren-descartes/) > [ \[About Pierre de Fermat\] It cannot be denied that he has had many exceptional ideas, and that he is a highly intelligent man. For… ](https://sms4smile.com/quotes/ren-descartes/about-pierre-de-fermat-it-cannot-be-denied-that-he-has-had-many/) [Rene Descartes](https://sms4smile.com/quotes/author/ren-descartes/) > [Science is practical philosophy.](https://sms4smile.com/quotes/ren-descartes/science-is-practical-philosophy/) [Rene Descartes](https://sms4smile.com/quotes/author/ren-descartes/) > [ “And what more am I? I look for aid to the imagination. \[But how mistakenly!\] I am not that assemblage of limbs we call… ](https://sms4smile.com/quotes/ren-descartes/and-what-more-am-i-i-look-for-aid-to-the-imagination-but-how/) [René Descartes](https://sms4smile.com/quotes/author/ren-descartes/) > [“And, in fine, of false sciences I thought I knew the worth sufficiently to escape being deceived by the professions of an alchemist, the…](https://sms4smile.com/quotes/ren-descartes/and-in-fine-of-false-sciences-i-thought-i-knew-the-worth-sufficiently/) [René Descartes](https://sms4smile.com/quotes/author/ren-descartes/) > [Nothing is more fairly distributed than common sense: no one thinks he needs more of it than he already has.](https://sms4smile.com/quotes/ren-descartes/nothing-is-more-fairly-distributed-than-common-sense-no-one-thinks-he/) [Rene Descartes](https://sms4smile.com/quotes/author/ren-descartes/) > [If I go for the alternative which is false, then obviously I shall be in error; if I take the other side, then it…](https://sms4smile.com/quotes/ren-descartes/if-i-go-for-the-alternative-which-is-false-then-obviously-i-shall-be/) [Rene Descartes](https://sms4smile.com/quotes/author/ren-descartes/) > [Everything is self-evident.](https://sms4smile.com/quotes/ren-descartes/everything-is-self-evident/) [Rene Descartes](https://sms4smile.com/quotes/author/ren-descartes/) > [Neither the true nor the false roots are always real; sometimes they are imaginary; that is, while we can always imagine as many roots…](https://sms4smile.com/quotes/ren-descartes/neither-the-true-nor-the-false-roots-are-always-real-sometimes-they/) [Rene Descartes](https://sms4smile.com/quotes/author/ren-descartes/) > [It is only intelligence that is divided equally between people because everybody thinks he/she is enough wise](https://sms4smile.com/quotes/ren-descartes/it-is-only-intelligence-that-is-divided-equally-between-people/) [René Descartes](https://sms4smile.com/quotes/author/ren-descartes/) [Explore all 232 Rene Descartes quotes ](https://sms4smile.com/quotes/author/ren-descartes/) ## More Amazement quotes > [We started this together, Leo. Seems only right you come along. You find us a ride, you're in." "Yes!" Leo pumped his fist. \*…](https://sms4smile.com/quotes/rick-riordan/we-started-this-together-leo-seems-only-right-you-come-along-you-find/) [Rick Riordan](https://sms4smile.com/quotes/author/rick-riordan/) > [When I got on the set of 'Saving Private Ryan,' I discovered, to my amazement, that Steven Spielberg is a gamer.](https://sms4smile.com/quotes/vin-diesel/when-i-got-on-the-set-of-saving-private-ryan-i-discovered-to-my/) [Vin Diesel](https://sms4smile.com/quotes/author/vin-diesel/) > [With education symmetrical and true we will take the dead mass buried by slavery's hand and touch them to life. This beauteous angel, which…](https://sms4smile.com/quotes/william-tecumseh-vernon/with-education-symmetrical-and-true-we-will-take-the-dead-mass-buried/) [William Tecumseh Vernon](https://sms4smile.com/quotes/author/william-tecumseh-vernon/) > [The very fact that we make such a to-do over golden weddings indicates our amazement at human endurance. The celebration is more in the…](https://sms4smile.com/quotes/ilka-chase/the-very-fact-that-we-make-such-a-to-do-over-golden-weddings/) [Ilka Chase](https://sms4smile.com/quotes/author/ilka-chase/) > [I think it wasn't so much that the White House altered me in any essential way as that I found the resources with which…](https://sms4smile.com/quotes/betty-ford/i-think-it-wasn-t-so-much-that-the-white-house-altered-me-in-any/) [Betty Ford](https://sms4smile.com/quotes/author/betty-ford/) > [He sees with amazement that our defeats are but the stepping stones to victory and that all his victories are stepping stones to ruin.…](https://sms4smile.com/quotes/winston-churchill/he-sees-with-amazement-that-our-defeats-are-but-the-stepping-stones/) [Winston Churchill](https://sms4smile.com/quotes/author/winston-churchill/) > [Sometime in the last ten years the best brains of the Occident discovered to their amazement that we live in an Environment. This discovery…](https://sms4smile.com/quotes/gary-snyder/sometime-in-the-last-ten-years-the-best-brains-of-the-occident/) [Gary Snyder](https://sms4smile.com/quotes/author/gary-snyder/) > [When one thinks of the wondrous glory of Christ, how astonishing that He can join with us! But more, when one thinks of His…](https://sms4smile.com/quotes/george-wigram/when-one-thinks-of-the-wondrous-glory-of-christ-how-astonishing-that/) [George Wigram](https://sms4smile.com/quotes/author/george-wigram/) > [Other people's marriages are a perpetual source of amazement.](https://sms4smile.com/quotes/patrick-o-brian/other-people-s-marriages-are-a-perpetual-source-of-amazement/) [Patrick O'Brian](https://sms4smile.com/quotes/author/patrick-o-brian/) > [Adlai Stevenson, himself a notable speaker, often reminisced about his last meeting with Churchill. I asked him on whom or what he had based…](https://sms4smile.com/quotes/william-bourke-cockran/adlai-stevenson-himself-a-notable-speaker-often-reminisced-about-his/) [William Bourke Cockran](https://sms4smile.com/quotes/author/william-bourke-cockran/) > [I realized a long time ago, with a certain amazement, that no mattter how important something is in your life, no matter how huge…](https://sms4smile.com/quotes/sharon-shinn/i-realized-a-long-time-ago-with-a-certain-amazement-that-no-mattter/) [Sharon Shinn](https://sms4smile.com/quotes/author/sharon-shinn/) > [Basically, I want to spend my time in retreat, but to my own amazement, I agreed to help with a project to start a…](https://sms4smile.com/quotes/tenzin-palmo/basically-i-want-to-spend-my-time-in-retreat-but-to-my-own-amazement/) [Tenzin Palmo](https://sms4smile.com/quotes/author/tenzin-palmo/) > [Ten times a day something happens to me like this - some strengthening throb of amazement - some good sweet empathic ping and swell.…](https://sms4smile.com/quotes/mary-oliver/ten-times-a-day-something-happens-to-me-like-this-some-strengthening/) [Mary Oliver](https://sms4smile.com/quotes/author/mary-oliver/) > [DREAM PREDICTION ELITE is the realization of true amazement in your audiences reactions. This is PURE GOLD - A REAL WINNER](https://sms4smile.com/quotes/banachek/dream-prediction-elite-is-the-realization-of-true-amazement-in-your/) [Banachek](https://sms4smile.com/quotes/author/banachek/) > [Poetry is a language in which man explores his own amazement.](https://sms4smile.com/quotes/christopher-fry/poetry-is-a-language-in-which-man-explores-his-own-amazement/) [Christopher Fry](https://sms4smile.com/quotes/author/christopher-fry/) [Browse all 241 Amazement quotes ](https://sms4smile.com/quotes/about/amazement/) ```json { "@context": "https://schema.org", "@graph": [ { "@type": "Quotation", "text": "But I cannot forget that, at other times I have been deceived in sleep by similar illusions; and, attentively considering those cases, I perceive so clearly that there exist no certain marks by which the state of waking can ever be distinguished from sleep, that I feel greatly astonished; and in amazement I almost persuade myself that I am now dreaming.", "creator": { "@type": "Person", "name": "Rene Descartes" }, "isPartOf": { "@id": "https://sms4smile.com/quotes/#website" }, "url": "https://sms4smile.com/quotes/ren-descartes/but-i-cannot-forget-that-at-other-times-i-have-been-deceived-in-sleep/", "about": { "@type": "Thing", "name": "Amazement" }, "@id": "https://sms4smile.com/quotes/ren-descartes/but-i-cannot-forget-that-at-other-times-i-have-been-deceived-in-sleep/#quotation", "image": { "@type": "ImageObject", "@id": "https://sms4smile.com/quotes/i/97f/ren-descartes-1376_amazement_but-i-cannot-forget-that-at-other-times_2028874.png", "contentUrl": "https://sms4smile.com/quotes/i/97f/ren-descartes-1376_amazement_but-i-cannot-forget-that-at-other-times_2028874.png", "url": "https://sms4smile.com/quotes/i/97f/ren-descartes-1376_amazement_but-i-cannot-forget-that-at-other-times_2028874.png", "width": 1080, "height": 1080, "caption": "“But I cannot forget that, at other times I have been deceived in sleep by similar illusions; and…” — Rene Descartes", "creditText": "SMS4Smile Quotes", "creator": { "@id": "https://sms4smile.com/quotes/#organization" } } }, { "@type": "BreadcrumbList", "itemListElement": [ { "@type": "ListItem", "position": 1, "name": "Home", "item": "https://sms4smile.com/" }, { "@type": "ListItem", "position": 2, "name": "Quotes", "item": "https://sms4smile.com/quotes/" }, { "@type": "ListItem", "position": 3, "name": "Rene Descartes", "item": "https://sms4smile.com/quotes/author/ren-descartes/" }, { "@type": "ListItem", "position": 4, "name": "But I cannot forget that, at...", "item": "https://sms4smile.com/quotes/ren-descartes/but-i-cannot-forget-that-at-other-times-i-have-been-deceived-in-sleep/" } ], "@id": "https://sms4smile.com/quotes/ren-descartes/but-i-cannot-forget-that-at-other-times-i-have-been-deceived-in-sleep/#breadcrumb" }, { "@type": "WebSite", "@id": "https://sms4smile.com/quotes/#website", "name": "SMS4Smile Quotes", "url": "https://sms4smile.com/quotes/", "publisher": { "@id": "https://sms4smile.com/quotes/#organization" } }, { "@type": "Organization", "@id": "https://sms4smile.com/quotes/#organization", "name": "SMS4Smile Quotes", "url": "https://sms4smile.com/quotes/", "logo": { "@type": "ImageObject", "url": "https://sms4smile.com/quotes/wp-content/themes/sq/assets/icons/icon-512.png", "width": 512, "height": 512 } } ] } ```