three dialogues-第5章

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　　　　　。　By　the　former　without　doubt。

　　　　　。　Is　it　not　plain　from　　that　microscopes
make　the　sight　more　penetrating；　and　represent　objects　as　they
would　appear　to　the　eye　in　case　it　were　naturally　endowed　with　a
most　exquisite　sharpness？

　　　　　。　It　is。

　　　　　。　Consequently　the　microscopical　representation　is　to
be　thought　that　which　best　sets　forth　the　real　nature　of　the
thing；　or　what　it　is　in　itself。　The　colours；　therefore；　by　it
perceived　are　more　genuine　and　real　than　those　perceived
otherwise。

　　　　　。　I　confess　there　is　something　in　what　you　say。

　　　　　。　Besides；　it　is　not　only　possible　but　manifest；　that
there　actually　are　animals　whose　eyes　are　by　nature　framed　to
perceive　those　things　which　by　reason　of　their　minuteness　escape
our　sight。　What　think　you　of　those　inconceivably　small　animals
perceived　by　glasses？　must　we　suppose　they　are　all　stark　blind？
Or；　in　case　they　see；　can　it　be　imagined　their　sight　hath　not　the
same　use　in　preserving　their　bodies　from　injuries；　which　appears
in　that　of　all　other　animals？　And　if　it　hath；　is　it　not　evident
they　must　see　particles　less　than　their　own　bodies；　which　will
present　them　with　a　far　different　view　in　each　object　from　that
which　strikes　our　senses？　Even　our　own　eyes　do　not　always
represent　objects　to　us　after　the　same　manner。　In　the　jaundice
every　one　knows　that　all　things　seem　yellow。　Is　it　not　therefore
highly　probable　those　animals　in　whose　eyes　we　discern　a　very
different　texture　from　that　of　ours；　and　whose　bodies　abound　with
different　humours；　do　not　see　the　same　colours　in　every　object
that　we　do？　From　all　which；　should　it　not　seem　to　follow　that　all
colours　are　equally　apparent；　and　that　none　of　those　which　we
perceive　are　really　inherent　in　any　outward　object？

　　　　　。　It　should。

　　　　　。　The　point　will　be　past　all　doubt；　if　you　consider
that；　in　case　colours　were　real　properties　or　affections　inherent
in　external　bodies；　they　could　admit　of　no　alteration　without
some　change　wrought　in　the　very　bodies　themselves：　but；　is　it　not
evident　from　what　hath　been　said　that；　upon　the　use　of
microscopes；　upon　a　change　happening　in　the　burnouts　of　the　eye；
or　a　variation　of　distance；　without　any　manner　of　real　alteration
｛186｝　in　the　thing　itself；　the　colours　of　any　object　are　either
changed；　or　totally　disappear？　Nay；　all　other　circumstances
remaining　the　same；　change　but　the　situation　of　some　objects；　and
they　shall　present　different　colours　to　the　eye。　The　same　thing
happens　upon　viewing　an　object　in　various　degrees　of　light。　And
what　is　more　known　than　that　the　same　bodies　appear　differently
coloured　by　candle…light　from　what　they　do　in　the　open　day？　Add
to　these　the　experiment　of　a　prism　which；　separating　the
heterogeneous　rays　of　light；　alters　the　colour　of　any　object；　and
will　cause　the　whitest　to　appear　of　a　deep　blue　or　red　to　the
naked　eye。　And　now　tell　me　whether　you　are　still　of　opinion　that
every　body　hath　its　true　real　colour　inhering　in　it；　and；　if　you
think　it　hath；　I　would　fain　know　farther　from　you；　what　certain
distance　and　position　of　the　object；　what　peculiar　texture　and
formation　of　the　eye；　what　degree　or　kind　of　light　is　necessary
for　ascertaining　that　true　colour；　and　distinguishing　it　from
apparent　ones。

　　　　　。　I　own　myself　entirely　satisfied；　that　they　are　all
equally　apparent；　and　that　there　is　no　such　thing　as　colour
really　inhering　in　external　bodies；　but　that　it　is　altogether　in
the　light。　And　what　confirms　me　in　this　opinion　is；　that　in
proportion　to　the　light　colours　are　still　more　or　less　vivid；　and
if　there　be　no　light；　then　are　there　no　colours　perceived。
Besides；　allowing　there　are　colours　on　external　objects；　yet；　how
is　it　possible　for　us　to　perceive　them？　For　no　external　body
affects　the　mind；　unless　it　acts　first　on　our　organs　of　sense。
But　the　only　action　of　bodies　is　motion；　and　motion　cannot　be
communicated　otherwise　than　by　impulse。　A　distant　object
therefore　cannot　act　on　the　eye；　nor　consequently　make　itself　or
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。