independently；　one　might　devote　close　consideration　and　inquiry。　At
  the　same　time　it　becomes　plain　from　them　that　as　the　eye　＇in　seeing＇
  is　affected　＇by　the　object　seen＇；　so　also　it　produces　a　certain　effect
  upon　it。　If　a　woman　chances　during　her　menstrual　period　to　look　into　a
  highly　polished　mirror；　the　surface　of　it　will　grow　cloudy　with　a
  blood…coloured　haze。　It　is　very　hard　to　remove　this　stain　from　a　new
  mirror；　but　easier　to　remove　from　an　older　mirror。　As　we　have　said
  before；　the　cause　of　this　lies　in　the　fact　that　in　the　act　of　sight
  there　occurs　not　only　a　passion　in　the　sense　organ　acted　on　by　the
  polished　surface；　but　the　organ；　as　an　agent；　also　produces　an　action；
  as　is　proper　to　a　brilliant　object。　For　sight　is　the　property　of　an
  organ　possessing　brilliance　and　colour。　The　eyes；　therefore；　have
  their　proper　action　as　have　other　parts　of　the　body。　Because　it　is
  natural　to　the　eye　to　be　filled　with　blood…vessels；　a　woman's　eyes；
  during　the　period　of　menstrual　flux　and　inflammation；　will　undergo　a
  change；　although　her　husband　will　not　note　this　since　his　seed　is　of
  the　same　nature　as　that　of　his　wife。　The　surrounding　atmosphere；
  through　which　operates　the　action　of　sight；　and　which　surrounds　the
  mirror　also；　will　undergo　a　change　of　the　same　sort　that　occurred
  shortly　before　in　the　woman's　eyes；　and　hence　the　surface　of　the
  mirror　is　likewise　affected。　And　as　in　the　case　of　a　garment；　the
  cleaner　it　is　the　more　quickly　it　is　soiled；　so　the　same　holds　true　in
  the　case　of　the　mirror。　For　anything　that　is　clean　will　show　quite
  clearly　a　stain　that　it　chances　to　receive；　and　the　cleanest　object
  shows　up　even　the　slightest　stain。　A　bronze　mirror；　because　of　its
  shininess；　is　especially　sensitive　to　any　sort　of　contact　（the
  movement　of　the　surrounding　air　acts　upon　it　like　a　rubbing　or
  pressing　or　wiping）；　on　that　account；　therefore；　what　is　clean　will
  show　up　clearly　the　slightest　touch　on　its　surface。　It　is　hard　to
  cleanse　smudges　off　new　mirrors　because　the　stain　penetrates　deeply
  and　is　suffused　to　all　parts；　it　penetrates　deeply　because　the
  mirror　is　not　a　dense　medium；　and　is　suffused　widely　because　of　the
  smoothness　of　the　object。　On　the　other　hand；　in　the　case　of　old
  mirrors；　stains　do　not　remain　because　they　do　not　penetrate　deeply；
  but　only　smudge　the　surface。
  From　this　therefore　it　is　plain　that　stimulatory　motion　is　set　up
  even　by　slight　differences；　and　that　sense…perception　is　quick　to
  respond　to　it；　and　further　that　the　organ　which　perceives　colour　is
  not　only　affected　by　its　object；　but　also　reacts　upon　it。　Further
  evidence　to　the　same　point　is　afforded　by　what　takes　place　in　wines；
  and　in　the　manufacture　of　unguents。　For　both　oil；　when　prepared；　and
  wine　become　rapidly　infected　by　the　odours　of　the　things　near　them；
  they　not　only　acquire　the　odours　of　the　things　thrown　into　or　mixed
  with　them；　but　also　those　of　the　things　which　are　placed；　or　which
  grow；　near　the　vessels　containing　them。
  In　order　to　answer　our　original　question；　let　us　now；　therefore；
  assume　one　proposition；　which　is　clear　from　what　precedes；　viz。　that
  even　when　the　external　object　of　perception　has　departed；　the
  impressions　it　has　made　persist；　and　are　themselves　objects　of
  perception：　and　＇let　us　assume＇；　besides；　that　we　are　easily
  deceived　respecting　the　operations　of　sense…perception　when　we　are
  excited　by　emotions；　and　different　persons　according　to　their
  different　emotions；　for　example；　the　coward　when　excited　by　fear；
  the　amorous　person　by　amorous　desire；　so　that；　with　but　little
  resemblance　to　go　upon；　the　former　thinks　he　sees　his　foes
  approaching；　the　latter；　that　he　sees　the　object　of　his　desire；　and
  the　more　deeply　one　is　under　the　influence　of　the　emotion；　the　less
  similarity　is　required　to　give　rise　to　these　illusory　impressions。
  Thus　too；　both　in　fits　of　anger；　and　also　in　all　states　of　appetite；
  all　men　become　easily　deceived；　and　more　so　the　more　their　emotions
  are　excited。　This　is　the　reason　too　why　persons　in　the　delirium　of
  fever　sometimes　think　they　see　animals　on　their　chamber　walls；　an
  illusion　arising　from　the　faint　resemblance　to　animals　of　the　markings
  thereon　when　put　together　in　patterns；　and　this　sometimes
  corresponds　with　the　emotional　states　of　the　sufferers；　in　such　a
  way　that；　if　the　latter　be　not　very　ill；　they　know　well　enough　that　it
  is　an　illusion；　but　if　the　illness　is　more　severe　they　actually　move
  according　to　the　appearances。　The　cause　of　these　occurrences　is　that
  the　faculty　in　virtue　of　which　the　controlling　sense　judges　is　not
  identical　with　that　in　virtue　of　which　presentations　come　before　the
  mind。　A　proof　of　this　is；　that　the　sun　presents　itself　as　only　a
  foot　in　diameter；　though　often　something　else　gainsays　the
  presentation。　Again；　when　the　fingers　are　crossed；　the　one　object
  ＇placed　between　them＇　is　felt　＇by　the　touch＇　as　two；　but　yet　we　deny
  that　it　is　two；　for　sight　is　more　authoritative　than　touch。　Yet；　if
  touch　stood　alone；　we　should　actually　have　pronounced　the　one　object
  to　be　two。　The　ground　of　such　false　judgements　is　that　any　appearances
  whatever　present　themselves；　not　only　when　its　object　stimulates　a
  sense；　but　also　when　the　sense　by　itself　alone　is　stimulated；　provided
  only　it　be　stimulated　in　the　same　manner　as　it　is　by　the　object。　For
  example；　to　persons　sailing　past　the　land　seems　to　move；　when　it　is
  really　the　eye　that　is　being　moved　by　something　else　＇the　moving　ship。＇
  3
  From　this　it　is　manifest　that　the　stimulatory　movements　based　upon
  sensory　impressions；　whether　the　latter　are　derived　from　external
  objects　or　from　causes　within　the　body；　present　themselves　not　only
  when　persons　are　awake；　but　also　then；　when　this　affection　which　is
  called　sleep　has　come　upon　them；　with　even　greater　impressiveness。　For
  by　day；　while　the　senses　and　the　intellect　are　working　together；
  they　（i。e。　such　movements）　are　extruded　from　consciousness　or
  obscured；　just　as　a　smaller　is　beside　a　larger　fire；　or　as　small
  beside　great　pains　or　pleasures；　though；　as　soon　as　the　latter　have
  ceased；　even　those　which　are　trifling　emerge　into　notice。　But　by　night
  ＇i。e。　in　sleep＇　owing　to　the　inaction　of　the　particular　senses；　and
  their　powerlessness　to　realize　themselves；　which　arises　from　the
  reflux　of　the　hot　from　the　exterior　parts　to　the　interior；　they
  ＇i。e。　the　above　'movements'＇　are　borne　in　to　the　head　quarters　of
  sense…perception；　and　there　display　themselves　as　the　disturbance
  （of　waking　life）　subsides。　We　must　suppose　that；　like　the　little
  eddies　which　are　being　ever　formed　in　rivers；　so　the　sensory　movements
  are　each　a　continuous　process；　often　remaining　like　what　they　were
  when　first　started；　but　often；　too；　broken　into　other　forms　by
  collisions　with　obstacles。　This　＇last　mentioned　point＇；　moreover；
  gives　the　reason　why　no　dreams　occur　in　sleep　immediately　after　meals；
  or　to　sleepers　who　are　extremely　young；　e。g。　to　infants。　The
  internal　movement　in　such　cases　is　excessive；　owing　to　the　heat
  generated　from　the　food。　Hence；　just　as　in　a　liquid；　if　one　vehemently
  disturbs　it；　sometimes　no　reflected　image　appears；　while　at　other
  times　one　appears；　indeed；　but　utterly　distorted；　so　as　to　seem
  quite　unlike　its　original；　while；　when　once　the　motion　has　ceased；　the
  reflected　images　are　clear　and　plain；　in　the　same　manner　during
  sleep　the　phantasms；　or　residuary　movements；　which　are　based　upon
  the　sensory　impressions；　become　sometimes　quite　obliterated　by　the
  above　described　motion　when　too　violent；　while　at　other　times　the
  sights　are　indeed　seen；　but　confused　and　weird；　and　the　dreams
  ＇which　then　appear＇　are　unhealthy；　like　those　of　persons　who　are
  atrabilious；　or　feverish；　or　intoxicated　with　wine。　For　all　such
  affections；　being　spirituous；　cause　much　commotion　and　disturbance。　In
  sanguineous　animals；　in　proportion　as　the　blood　becomes　calm；　and　as
  its　purer　are　separated　from　its　less　pure　elements；　the　fact　that　the
  movement；　based　on　impressions　derived　from　each　of　the　organs　of
  sense；　is　preserved　in　its　integrity；　renders　the　dreams　healthy；
  causes　a　＇clear＇　image　to　present　itself；　and　makes　the　dreamer　think；
  owing　to　the　effects　borne　in　from　the　organ　of　sight；　that　he
  actually　sees；　and　owing　to　those　which　come　from　the　organ　of
  hearing；　that　he　really　hears；　and　so　on　with　those　also　which　proceed
  from　the　other　sensory　organs。　For　it　is　owing　to　the　fact　that　the
  movement　which　reaches　the　primary　organ　of　sense　comes　from　them；
  that　one　even　when　awake　believes　himself　to　see；　or　hear；　or
  otherwise　perceive；　just　as　it　is　from　a　belief　that　the　organ　of
  sight　is　being　stimulated；　though　in　reality　not　so　stimul