ought　not　the　less　carefully　to　refrain　from　giving　credence　to　these　opinions　than　to　that　which　is　manifestly　false；　if　I　desire　to　arrive　at　any　certainty　＇in　the　sciences＇。　　　　　　But　it　is　not　sufficient　to　have　made　these　remarks；　we　must　also　be　careful　to　keep　them　in　mind。　　For　these　ancient　and　commonly　held　opinions　still　revert　frequently　to　my　mind；　long　and　familiar　custom　having　given　them　the　right　to　occupy　my　mind　against　my　inclination　and　rendered　them　almost　masters　of　my　belief；　nor　will　I　ever　lose　the　habit　of　deferring　to　them　or　of　placing　my　confidence　in　them；　so　long　as　I　consider　them　as　they　really　are；　i。e。　opinions　in　some　measure　doubtful；　as　I　have　just　shown；　and　at　the　same　time　highly　probable；　so　that　there　is　much　more　reason　to　believe　in　than　to　deny　them。　　That　is　why　I　consider　that　I　shall　not　be　acting　amiss；　if；　taking　of　set　purpose　a　contrary　belief；　I　allow　myself　to　be　deceived；　and　for　a　certain　time　pretend　that　all　these　opinions　are　entirely　false　and　imaginary；　until　at　last；　having　thus　balanced　my　former　prejudices　with　my　latter　＇so　that　they　cannot　divert　my　opinions　more　to　one　side　than　to　the　other＇；　my　judgment　will　no　longer　be　dominated　by　bad　usage　or　turned　away　from　the　right　knowledge　of　the　truth。　　For　I　am　assured　that　there　can　be　neither　peril　nor　error　in　this　course；　and　that　I　cannot　at　present　yield　too　much　to　distrust；　since　I　am　not　considering　the　question　of　action；　but　only　of　knowledge。　　　　　　I　shall　then　suppose；　not　that　God　who　is　supremely　good　and　the　fountain　of　truth；　but　some　evil　genius　not　less　powerful　than　deceitful；　has　employed　his　whole　energies　in　deceiving　me；　I　shall　consider　that　the　heavens；　the　earth；　colours；　figures；　sound；　and　all　other　external　things　are　nought　but　the　illusions　and　dreams　of　which　this　genius　has　availed　himself　in　order　to　lay　traps　for　my　credulity；　I　shall　consider　myself　as　having　no　hands；　no　eyes；　no　flesh；　no　blood；　nor　any　senses；　yet　falsely　believing　myself　to　possess　all　these　things；　I　shall　remain　obstinately　attached　to　this　idea；　and　if　by　this　means　it　is　not　in　my　power　to　arrive　at　the　knowledge　of　any　truth；　I　may　at　least　do　what　is　in　my　power　＇i。e。　suspend　my　judgment＇；　and　with　firm　purpose　avoid　giving　credence　to　any　false　thing；　or　being　imposed　upon　by　this　arch　deceiver；　however　powerful　and　deceptive　he　may　be。　　But　this　task　is　a　laborious　one；　and　insensibly　a　certain　lassitude　leads　me　into　the　course　of　my　ordinary　life。　　And　just　as　a　captive　who　in　sleep　enjoys　an　imaginary　liberty；　when　he　begins　to　suspect　that　his　liberty　is　but　a　dream；　fears　to　awaken；　and　conspires　with　these　agreeable　illusions　that　the　deception　may　be　prolonged；　so　insensibly　of　my　own　accord　I　fall　back　into　my　former　opinions；　and　I　dread　awakening　from　this　slumber；　lest　the　laborious　wakefulness　which　would　follow　the　tranquillity　of　this　repose　should　have　to　be　spent　not　in　daylight；　but　in　the　excessive　darkness　of　the　difficulties　which　have　just　been　discussed。　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　Meditation　II　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　Of　the　Nature　of　the　Human　Mind；　and　that　it　is　more　easily　　　　　　　　　　　　　　　　　　　　　　known　than　the　Body。　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　The　Meditation　of　yesterday　filled　my　mind　with　so　many　doubts　that　it　is　no　longer　in　my　power　to　forget　them。　　And　yet　I　do　not　see　in　what　manner　I　can　resolve　them；　and；　just　as　if　I　had　all　of　a　sudden　fallen　into　very　deep　water；　I　am　so　disconcerted　that　I　can　neither　make　certain　of　setting　my　feet　on　the　bottom；　nor　can　I　swim　and　so　support　myself　on　the　surface。　　I　shall　nevertheless　make　an　effort　and　follow　anew　the　same　path　as　that　on　which　I　yesterday　entered；　i。e。　I　shall　proceed　by　setting　aside　all　that　in　which　the　least　doubt　could　be　supposed　to　exist；　just　as　if　I　had　discovered　that　it　was　absolutely　false；　and　I　shall　ever　follow　in　this　road　until　I　have　met　with　something　which　is　certain；　or　at　least；　if　I　can　do　nothing　else；　until　I　have　learned　for　certain　that　there　is　nothing　in　the　world　that　is　certain。　Archimedes；　in　order　that　he　might　draw　the　terrestrial　globe　out　of　its　place；　and　transport　it　elsewhere；　demanded　only　that　one　point　should　be　fixed　and　immoveable；　in　the　same　way　I　shall　have　the　right　to　conceive　high　hopes　if　I　am　happy　enough　to　discover　one　thing　only　which　is　certain　and　indubitable。　　　　　　I　suppose；　then；　that　all　the　things　that　I　see　are　false；　I　persuade　myself　that　nothing　has　ever　existed　of　all　that　my　fallacious　memory　represents　to　me。　　I　consider　that　I　possess　no　senses；　I　imagine　that　body；　figure；　extension；　movement　and　place　are　but　the　fictions　of　my　mind。　　What；　then；　can　be　esteemed　as　true？　　Perhaps　nothing　at　all；　unless　that　there　is　nothing　in　the　world　that　is　certain。　　　　　　But　how　can　I　know　there　is　not　something　different　from　those　things　that　I　have　just　considered；　of　which　one　cannot　have　the　slightest　doubt？　　Is　there　not　some　God；　or　some　other　being　by　whatever　name　we　call　it；　who　puts　these　reflections　into　my　mind？　　That　is　not　necessary；　for　is　it　not　possible　that　I　am　capable　of　producing　them　myself？　　I　myself；　am　I　not　at　least　something？　　But　I　have　already　denied　that　I　had　senses　and　body。　　Yet　I　hesitate；　for　what　follows　from　that？　　Am　I　so　dependent　on　body　and　senses　that　I　cannot　exist　without　these？　　But　I　was　persuaded　that　there　was　nothing　in　all　the　world；　that　there　was　no　heaven；　no　earth；　that　there　were　no　minds；　nor　any　bodies：　　was　I　not　then　likewise　persuaded　that　I　did　not　exist？　　Not　at　all；　of　a　surety　I　myself　did　exist　since　I　persuaded　myself　of　something　＇or　merely　because　I　thought　of　something＇。　　But　there　is　some　deceiver　or　other；　very　powerful　and　very　cunning；　who　ever　employs　his　ingenuity　in　deceiving　me。　　Then　without　doubt　I　exist　also　if　he　deceives　me；　and　let　him　deceive　me　as　much　as　he　will；　he　can　never　cause　me　to　be　nothing　so　long　as　I　think　that　I　am　something。　　So　that　after　having　reflected　well　and　carefully　examined　all　things；　we　must　come　to　the　definite　conclusion　that　this　proposition：　　I　am；　I　exist；　is　necessarily　true　each　time　that　I　pronounce　it；　or　that　I　mentally　conceive　it。　　　　　　But　I　do　not　yet　know　clearly　enough　what　I　am；　I　who　am　certain　that　I　am；　and　hence　I　must　be　careful　to　see　that　I　do　not　imprudently　take　some　other　object　in　place　of　myself；　and　thus　that　I　do　not　go　astray　in　respect　of　this　knowledge　that　I　hold　to　be　the　most　certain　and　most　evident　of　all　that　I　have　formerly　learned。　　That　is　why　I　shall　now　consider　anew　what　I　believed　myself　to　be　before　I　embarked　upon　these　last　reflections；　and　of　my　former　opinions　I　shall　withdraw　all　that　might　even　in　a　small　degree　be　invalidated　by　the　reasons　which　I　have　just　brought　forward；　in　order　that　there　may　be　nothing　at　all　left　beyond　what　is　absolutely　certain　and　indubitable。　　　　　　What　then　did　I　formerly　believe　myself　to　be？　Undoubtedly　I　believed　myself　to　be　a　man。　　But　what　is　a　man？　Shall　I　say　a　reasonable　animal？　　Certainly　not；　for　then　I　should　have　to　inquire　what　an　animal　is；　and　what　is　reasonable；　and　thus　from　a　single　question　I　should　insensibly　fall　into　an　infinitude　of　others　more　difficult；　and　I　should　not　wish　to　waste　the　little　time　and　leisure　remaining　to　me　in　trying　to　unravel　subtleties　like　these。　But　I　shall　rather　stop　here　to　consider　the　thoughts　which　of　themselves　spring　up　in　my　mind；　and　which　were　not　inspired　by　anything　beyond　my　own　nature　alone　when　I　applied　myself　to　the　consideration　of　my　being。　　In　the　first　place；　the；　I　considered　myself　as　having　a　face；　hands；　arms；　and　all　that　system　of　members　composed　on　bones　and　flesh　as　seen　in　a　corpse　which　I　designated　by　the　name　of　body。　　In　addition　to　this　I　considered　that　I　was　nourished；　that　I　walked；　that　I　felt；　and　that　I　thought；　and　I　referred　all　these　actions　to　the　soul：　　but　I　did　not　stop　to　consider　what　the　soul　was；　or　if　I　did　stop；　I　imagined　that　it　was　something　extremely　rare　and　subtle　like　a　wind；　a　flame；　or　an　ether；　which　was　spread　throughout　my　grosser　parts。　　As　to　body　I　had　no　manner　of　doubt　about　its　nature；　but　thought　I　had　a　very　clear　knowledge　of　it；　and　if　I　had　desired　to　explain　it　according　to　the　notions　that　I　had　then　formed　of　it；　I　should　have　described　it　thus：　　By　the　body　I　understand　all　that　which　can　be　defined　by　a　certain　figure：　　something　which　can　be　confined　in　a　certain　place；　and　which　can　fill　a　given　space　in　such　a　way　that　every　other　body　will　be　excluded　from　it；　which　can　be　perceived　either　by　tough；　or　by　sight；　or　by　hearing；　or　by　taste；　or　by　smell：　　which　can　be　moved　in　many　ways　not；　in　truth；　by　itself；　but　by　something　which　is　foreign　to　it；　by　which　it　is　touched　＇and　from　which　it　receives　impressions＇：　　for　to　have　the　power　of　self…movement；　as　also　of　feeling　or　of　thinking；　I　did　not　consider　to　appertain　to　the　nature　of　body：　　on　the　contrary；　I　was　rather　astonished　to　find　that　faculties　similar　to　them　existed　in　some　bodies。　　　　　　But　what　am　I；　now　that　I　suppose　that　there　is　a　certain　genius　which　is　extremely　powerful；　and；　if　I　may　say　so；　malicious；　who　employs　all　his　powers　in　deceivi