its　properties　perceivable　to　the　soul。　Whence　it　plainly　follows
  that　it　is　immediately　some　contiguous　substance；　which；
  operating　on　the　eye；　occasions　a　perception　of　colours：　and　such
  is　light。
  。　Howl　is　light　then　a　substance？
  。。　I　tell　you；　Philonous；　external　light　is　nothing　but
  a　thin　fluid　substance；　whose　minute　particles　being　agitated
  with　a　brisk　motion；　and　in　various　manners　reflected　from　the
  different　surfaces　of　outward　objects　to　the　eyes；　communicate
  different　motions　to　the　optic　nerves；　which；　being　propagated　to
  the　brain；　cause　therein　various　impressions；　and　these　are
  attended　with　the　sensations　of　red；　blue；　yellow；　&c。
  。　It　seems　then　the　light　doth　no　more　than　shake　the
  optic　nerves。　｛187｝
  。　Nothing　else。
  。　And　consequent　to　each　particular　motion　of　the
  nerves；　the　mind　is　affected　with　a　sensation；　which　is　some
  particular　colour。
  。　Right。
  。　And　these　sensations　have　no　existence　without　the
  mind。
  。　They　have　not。
  。　How　then　do　you　affirm　that　colours　are　in　the
  light；　since　by　　you　understand　a　corporeal　substance
  external　to　the　mind？
  。　Light　and　colours；　as　immediately　perceived　by　us；　I
  grant　cannot　exist　without　the　mind。　But　in　themselves　they　are
  only　the　motions　and　configurations　of　certain　insensible
  particles　of　matter。
  。　Colours　then；　in　the　vulgar　sense；　or　taken　for　the
  immediate　objects　of　sight；　cannot　agree　to　any　but　a　perceiving
  substance。
  。　That　is　what　I　say。
  。　Well　then；　since　you　give　up　the　point　as　to　those
  sensible　qualities　which　are　alone　thought　colours　by　all　mankind
  beside；　you　may　hold　what　you　please　with　regard　to　those
  invisible　ones　of　the　philosophers。　It　is　not　my　business　to
  dispute　about　；　only　I　would　advise　you　to　bethink
  yourself；　whether；　considering　the　inquiry　we　are　upon；　it　be
  prudent　for　you　to　affirm　　；　。　Are　not　these　shocking
  notions；　and　are　not　they　subject　to　as　many　ridiculous
  inferences；　as　those　you　were　obliged　to　renounce　before　in　the
  case　of　sounds？
  。　I　frankly　own；　Philonous；　that　it　is　in　vain　to
  longer。　Colours；　sounds；　tastes；　in　a　word　all　those　termed
  ；　have　certainly　no　existence　without　the
  mind。　But　by　this　acknowledgment　I　must　not　be　supposed　to
  derogate；　the　reality　of　Matter；　or　external　objects；　seeing　it
  is　no　more　than　several　philosophers　maintain；　who　nevertheless
  are　the　farthest　imaginable　from　denying　Matter。　For　the　clearer
  understanding　of　this；　you　must　know　sensible　qualities　are　by
  philosophers　divided　into　　and　。　The　former
  are　Extension；　Figure；　Solidity；　Gravity；　Motion；　and　Rest；　｛188｝
  and　these　they　hold　exist　really　in　bodies。　The　latter　are　those
  above　enumerated；　or；　briefly；　；　which　they　assert　are　only　so　many　sensations　or　ideas
  existing　nowhere　but　in　the　mind。　But　all　this；　I　doubt　not；　you
  are　apprised　of。　For　my　part；　I　have　been　a　long　time　sensible
  there　was　such　an　opinion　current　among　philosophers；　but　was
  never　thoroughly　convinced　of　its　truth　until　now。
  。　You　are　still　then　of　opinion　that　　and
  inherent　in　external　unthinking　substances？
  。　I　am。
  。　But　what　if　the　same　arguments　which　are　brought
  against　Secondary　Qualities　will　hold　good　against　these　also？
  。　Why　then　I　shall　be　obliged　to　think；　they　too　exist
  only　in　the　mind。
  。　Is　it　your　opinion　the　very　figure　and　extension
  which　you　perceive　by　sense　exist　in　the　outward　object　or
  material　substance？
  。　It　is。
  。　Have　all　other　animals　as　good　grounds　to　think　the
  same　of　the　figure　and　extension　which　they　see　and　feel？
  。　Without　doubt；　if　they　have　any　thought　at　all。
  。　Answer　me；　Hylas。　Think　you　the　senses　were　bestowed
  upon　all　animals　for　their　preservation　and　well…being　in　life？
  or　were　they　given　to　men　alone　for　this　end？
  。　I　make　no　question　but　they　have　the　same　use　in　all
  other　animals。
  。　If　so；　is　it　not　necessary　they　should　be　enabled　by
  them　to　perceive　their　own　limbs；　and　those　bodies　which　are
  capable　of　harming　them？
  。　Certainly。
  。　A　mite　therefore　must　be　supposed　to　see　his　own
  foot；　and　things　equal　or　even　less　than　it；　as　bodies　of　some
  considerable　dimension；　though　at　the　same　time　they　appear　to
  you　scarce　discernible；　or　at　best　as　so　many　visible　points？
  。　I　cannot　deny　it。
  。　And　to　creatures　less　than　the　mite　they　will　seem
  yet　larger？
  。　They　will。
  。　Insomuch　that　what　you　can　hardly　discern　will　to
  another　extremely　minute　animal　appear　as　some　huge　mountain？
  ｛189｝
  。　All　this　I　grant。
  。　Can　one　and　the　same　thing　be　at　the　same　time　in
  itself　of　different　dimensions？
  。　That　were　absurd　to　imagine。
  。　But；　from　what　you　have　laid　down　it　follows　that
  both　the　extension　by　you　perceived；　and　that　perceived　by　the
  mite　itself；　as　likewise　all　those　perceived　by　lesser　animals；
  are　each　of　them　the　true　extension　of　the　mite's　foot；　that　is
  to　say；　by　your　own　principles　you　are　led　into　an　absurdity。
  。　There　seems　to　be　some　difficulty　in　the　point。
  。　Again；　have　you　not　acknowledged　that　no　real
  inherent　property　of　any　object　can　be　changed　without　some
  change　in　the　thing　itself？
  。　I　have。
  。　But；　as　we　approach　to　or　recede　from　an　object；　the
  visible　extension　varies；　being　at　one　distance　ten　or　a　hundred
  times　greater　than　another。　Doth　it　not　therefore　follow　from
  hence　likewise　that　it　is　not　really　inherent　in　the　object？
  。　I　own　I　am　at　a　loss　what　to　think。
  。　Your　judgment　will　soon　be　determined；　if　you　will
  venture　to　think　as　freely　concerning　this　quality　as　you　have
  done　concerning　the　rest。　Was　it　not　admitted　as　a　good　argument；
  that　neither　heat　nor　cold　was　in　the　water；　because　it　seemed
  warm　to　one　hand　and　cold　to　the　other？
  。　It　was。
  。　Is　it　not　the　very　same　reasoning　to　conclude；　there
  is　no　extension　or　figure　in　an　object；　because　to　one　eye　it
  shall　seem　little；　smooth；　and　round；　when　at　the　same　time　it
  appears　to　the　other；　great；　uneven；　and　regular？
  。　The　very　same。　But　does　this　latter　fact　ever　happen？
  。　You　may　at　any　time　make　the　experiment；　by　looking
  with　one　eye　bare；　and　with　the　other　through　a　microscope。
  。　I　know　not　how　to　maintain　it；　and　yet　I　am　loath　to
  give　up　；　I　see　so　many　odd　consequences　following
  upon　such　a　concession。
  。　Odd；　say　you？　After　the　concessions　already　made；　I
  hope　you　will　stick　at　nothing　for　its　oddness。　＇But；　on　the
  other　hand；　should　it　not　seem　very　odd；　if　the　general　reasoning
  ｛190｝　which　includes　all　other　sensible　qualities　did　not　also
  include　extension？　If　it　be　allowed　that　no　idea；　nor　anything
  like　an　idea；　can　exist　in　an　unperceiving　substance；　then　surely
  it　follows　that　no　figure；　or　mode　of　extension；　which　we　can
  either　perceive；　or　imagine；　or　have　any　idea　of；　can　be　really
  inherent　in　Matter；　not　to　mention　the　peculiar　difficulty　there
  must　be　in　conceiving　a　material　substance；　prior　to　and　distinct
  from　extension　to　be　the　　of　extension。　Be　the
  sensible　quality　what　it　will　　figure；　or　sound；　or　colour；　it
  seems　alike　impossible　it　should　subsist　in　that　which　doth　not
  perceive　it。＇＇2＇
  。　I　give　up　the　point　for　the　present；　reserving　still
  a　right　to　retract　my　opinion；　in　case　I　shall　hereafter　discover
  any　false　step　in　my　progress　to　it。
  。　That　is　a　right　you　cannot　be　denied。　Figures　and
  extension　being　despatched；　we　proceed　next　to　。　Can　a
  real　motion　in　any　external　body　be　at　the　same　time　very　swift
  and　very　slow？
  。　It　cannot。
  。　Is　not　the　motion　of　a　body　swift　in　a　reciprocal
  proportion　to　the　time　it　takes　up　in　describing　any　given　space？
  Thus　a　body　that　describes　a　mile　in　an　hour　moves　three　times
  faster　than　it　would　in　case　it　described　only　a　mile　in　three
  hours。
  。　I　agree　with　you。
  。　And　is　not　time　measured　by　the　succession　of　ideas
  in　our　minds？
  。　It　is。
  。　And　is　it　not　possible　ideas　should　succeed　one
  another　twice　as　fast　in　your　mind　as　they　do　in　mine；　or　in　that
  of　some　spirit　of　another　kind？
  。　I　own　it。
  。　Consequently　the　same　body　may　to　another　seem　to
  perform　its　motion　over　any　space　in　half　the　time　that　it　doth
  to　you。　And　the　same　reasoning　will　hold　as　to　any　other
  proportion：　that　is　to　say；　according　to　your　principles　（since
  the　motions　perceived　are　both　really　in　the　object）　it　is
  possible　one　and　the　same　body　shall　be