thoughts on man- 第53部分

SECTION　I。

It　can　scarcely　be　imputed　to　me　as　profane；　if　I　venture　to　put　down　a　few　sceptical　doubts　on　the　science　of　astronomy。　　All　branches　of　knowledge　are　to　be　considered　as　fair　subjects　of　enquiry：　　and　he　that　has　never　doubted；　may　be　said；　in　the　highest　and　strictest　sense　of　the　word；　never　to　have　believed。

The　first　volume　that　furnished　to　me　the　groundwork　of　the　following　doubts；　was　the　book　commonly　known　by　the　name　of　Guthrie's　Geographical　Grammar；　many　parts　and　passages　of　which　engaged　my　attention　in　my　own　study；　in　the　house　of　a　rural　schoolmaster；　in　the　year　1772。　　I　cannot　therefore　proceed　more　fairly　than　by　giving　here　an　extract　of　certain　passages　in　that　book；　which　have　relation　to　the　present　subject。　　I　know　not　how　far　they　have　been　altered　in　the　edition　of　Guthrie　which　now　lies　before　me；　from　the　language　of　the　book　then　in　my　possession；　but　I　feel　confident　that　in　the　main　particulars　they　continue　the　same＇42＇。

＇42＇　The　article　Astronomy；　in　this　book；　appears　to　have　been　written　by　the　well　known　James　Ferguson。


〃In　passing　rapidly　over　the　heavens　with　his　new　telescope；　the　universe　increased　under　the　eye　of　Herschel；　44；000　stars；　seen　in　the　space　of　a　few　degrees；　seemed　to　indicate　that　there　were　seventy…five　millions　in　the　heavens。　　But　what　are　all　these；　when　compared　with　those　that　fill　the　whole　expanse；　the　boundless　field　of　aether？

〃The　immense　distance　of　the　fixed　stars　from　our　earth；　and　from　each　other；　is　of　all　considerations　the　most　proper　for　raising　our　ideas　of　the　works　of　God。　　Modern　discoveries　make　it　probable　that　each　of　these　stars　is　a　sun；　having　planets　and　comets　revolving　round　it；　as　our　sun　has　the　earth　and　other　planets　revolving　round　him。A　ray　of　light；　though　its　motion　is　so　quick　as　to　be　commonly　thought　instantaneous；　takes　up　more　time　in　travelling　from　the　stars　to　us；　than　we　do　in　making　a　West…India　voyage。　　A　sound；　which；　next　to　light；　is　considered　as　the　quickest　body　we　are　acquainted　with；　would　not　arrive　to　us　from　thence　in　50；000　years。　　And　a　cannon…ball；　flying　at　the　rate　of　480　miles　an　hour；　would　not　reach　us　in　700；000　years。

〃From　what　we　know　of　our　own　system；　it　may　be　reasonably　concluded；　that　all　the　rest　are　with　equal　wisdom　contrived；　situated；　and　provided　with　accommodations　for　rational　inhabitants。

〃What　a　sublime　idea　does　this　suggest　to　the　human　imagination；　limited　as　are　its　powers；　of　the　works　of　the　Creator！　　Thousands　and　thousands　of　suns；　multiplied　without　end；　and　ranged　all　around　us；　at　immense　distances　from　each　other；　attended　by　ten　thousand　times　ten　thousand　worlds；　all　in　rapid　motion；　yet　calm；　regular　and　harmonious；　invariably　keeping　the　paths　prescribed　them：　　and　these　worlds　peopled　with　myriads　of　intelligent　beings；　formed　for　endless　progression　in　perfection　and　felicity！〃

The　thought　that　would　immediately　occur　to　a　dispassionate　man　in　listening　to　this　statement；　would　be；　What　a　vast　deal　am　I　here　called　on　to　believe！

Now　the　first　rule　of　sound　and　sober　judgment；　in　encountering　any　story；　is　that；　in　proportion　to　the　magnitude　and　seemingly　incredible　nature　of　the　propositions　tendered　to　our　belief；　should　be　the　strength　and　impregnable　nature　of　the　evidence　by　which　those　propositions　are　supported。

It　is　not　here；　as　in　matters　of　religion；　that　we　are　called　upon　by　authority　from　on　high　to　believe　in　mysteries；　in　things　above　our　reason；　or；　as　it　may　be；　contrary　to　our　reason。　　No　man　pretends　to　a　revelation　from　heaven　of　the　truths　of　astronomy。　　They　have　been　brought　to　light　by　the　faculties　of　the　human　mind；　exercised　upon　such　facts　and　circumstances　as　our　industry　has　set　before　us。

To　persons　not　initiated　in　the　rudiments　of　astronomical　science；　they　rest　upon　the　great　and　high…sounding　names　of　Galileo；　Kepler；　Halley　and　Newton。　　But；　though　these　men　are　eminently　entitled　to　honour　and　gratitude　from　their　fellow…mortals；　they　do　not　stand　altogether　on　the　same　footing　as　Matthew；　Mark；　Luke　and　John；　by　whose　pens　has　been　recorded　〃every　word　that　proceedeth　out　of　the　mouth　of　God。〃

The　modest　enquirer　therefore；　without　pretending　to　put　himself　on　an　equality　with　these　illustrious　men；　may　be　forgiven；　when　he　permits　himself　to　suggest　a　few　doubts；　and　presumes　to　examine　the　grounds　upon　which　he　is　called　upon　to　believe　all　that　is　contained　in　the　above　passages。

Now　the　foundations　upon　which　astronomy；　as　here　delivered；　is　built；　are；　first；　the　evidence　of　our　senses；　secondly；　the　calculations　of　the　mathematician；　and；　in　the　third　place；　moral　considerations。　　These　have　been　denominated　respectively；　practical　astronomy；　scientific；　and　theoretical。

As　to　the　first　of　these；　it　is　impossible　for　us　on　this　occasion　not　to　recollect　what　has　so　often　occurred　as　to　have　grown　into　an　every…day　observation；　of　the　fallibility　of　our　senses。

It　may　be　doubted　however　whether　this　is　a　just　statement。　　We　are　not　deceived　by　our　senses；　but　deceived　in　the　inference　we　make　from　our　sensations。　　Our　sensations　respecting　what　we　call　the　external　world；　are　chiefly　those　of　length；　breadth　and　solidity；　hardness　and　softness；　heat　and　cold；　colour；　smell；　sound　and　taste。　　The　inference　which　the　generality　of　mankind　make　in　relation　to　these　sensations　is；　that　there　is　something　out　of　ourselves　corresponding　to　the　impressions　we　receive；　in　other　words；　that　the　causes　of　our　sensations　are　like　to　the　sensations　themselves。　　But　this　is；　strictly　speaking；　an　inference；　and；　if　the　cause　of　a　sensation　is　not　like　the　sensation；　it　cannot　precisely　be　affirmed　that　our　senses　deceive　us。　　We　know　what　passes　in　the　theatre　of　the　mind；　but　we　cannot　be　said　absolutely　to　know　any　thing；　more。

Modern　philosophy　has　taught　us；　in　certain　cases；　to　controvert　the　position；　that　the　causes　of　our　sensations　are　like　to　the　sensations　themselves。　　Locke　in　particular　has　called　the　attention　of　the　reasoning　part　of　mankind　to　the　consideration；　that　heat　and　cold；　sweet　and　bitter；　and　odour　offensive　or　otherwise；　are　perceptions；　which　imply　a　percipient　being；　and　cannot　exist　in　inanimate　substances。　　We　might　with　equal　propriety　ascribe　pain　to　the　whip　that　beats　us；　or　pleasure　to　the　slight　alternation　of　contact　in　the　person　or　thing　that　tickles　us；　as　suppose　that　heat　and　cold；　or　taste；　or　smell　are　any　thing　but　sensations。

The　same　philosophers　who　have　called　our　attention　to　these　remarks；　have　proceeded　to　shew　that　the　causes　of　our　sensations　of　sound　and　colour　have　no　precise　correspondence；　do　not　tally　with　the　sensations　we　receive。　　Sound　is　the　result　of　a　percussion　of　the　air。　　Colour　is　produced　by　the　reflection　of　the　rays　of　light；　so　that　the　same　object；　placed　in　a　position；　different　as　to　the　spectator；　but　in　itself　remaining　unaltered；　will　produce　in　him　a　sensation　of　different　colours；　or　shades　of　colour；　now　blue；　now　green；　now　brown；　now　black；　and　so　on。　　This　is　the　doctrine　of　Newton；　as　well　as　of　Locke。

It　follows　that；　if　there　were　no　percipient　being　to　receive　these　sensations；　there　would　be　no　heat　or　cold；　no　taste；　no　smell；　no　sound；　and　no　colour。

Aware　of　this　difference　between　our　sensations　in　certain　cases　and　the　causes　of　these　sensations；　Locke　has　divided　the　qualities　of　substances　in　the　material　universe　into　primary　and　secondary；　the　sensations　we　receive　of　the　primary　representing　the　actual　qualities　of　material　substances；　but　the　sensations　we　receive　of　what　he　calls　the　secondary　having　no　proper　resemblance　to　the　causes　that　produce　them。

Now；　if　we　proceed　in　the　spirit　of　severe　analysis　to　examine　the　primary　qualities　of　matter；　we　shall　not　perhaps　find　so　marked　a　distinction　between　those　and　the　secondary；　as　the　statement　of　Locke　would　have　led　us　to　imagine。

The　Optics　of　Newton　were　published　fourteen　years　later　than　Locke's　Essay　concerning　Human　Understanding。

In　endeavouring　to　account　for　the　uninterrupted　transmission　of　rays　of　light　through　transparent　substances；　however　hard　they　may　be　found　to　be；　Newton　has　these　observations。

〃Bodies　are　much　more　rare　and　porous；　than　is　commonly　believed。

Water　is　nineteen　times　lighter；　and　by　consequence　nineteen　times　rarer；　than　gold；　and　gold　is　so　rare；　as　very　readily；　and　without　the　least　opposition；　to　transmit　the　magnetic　effluvia；　and　easily　to　admit　quicksilver　into　its　pores；　and　to　let　water　pass　through　it。　　From　all　which　we　may　conclude；　that　gold　has　more　pores　than　solid　parts；　and　by　consequence　that　water　has　above　forty　times　more　pores　than　parts。　　And　he　that　shall　find　out　an　hypothesis；　by　which　water　may　be　so　rare；　and　yet　not　capable　of　compression　by　force；　may　doubtless；　by　the　same　hypothesis；　make　gold；　and　water；　and　all　other　bodies；　as　much　rarer　as　he　pleases；　so　that　light　may　find　a　ready　passage　through　transparent　substances＇43＇。〃

＇43＇　Newton；　Optics；　Book　II；　Part　III；　Prop。　viii。


Again：　　〃The　colours　of　bodies　arise　from　the　magnitude　of　the　particles　that　reflect　them。　　Now；　if　we　conceive　these　particles　of　bodies　to　be　so　disposed　among　themselves；　that　the　intervals；　or　empty　spaces　between　them；　may　be　equal　in　magnitude　to　them　all；　and　that　these　particles　may　be　composed　of　other　particles　much　smaller；　which　have　as　much　empty　space　between　them　as　equals　all　the　magnitudes　of　these　smaller　particles；　and　that　in　like　manner　these　smaller　particles　are　again　composed　of　others　much　smaller；　all　which　together　are　equal　to　all　the　pores；　or　empty　spaces；　between　them；　and　so　on　perpetually　till　you　come　to　solid　particles；　such　as　have　no　pores；　or　empty　spaces　within　them：　　and　if　in　any　gross　body　there　be；　for　instance；　three　such　degrees　of　particles；　the　least　of　which　are　solid；　this　body　will　have　seven　times　more　pores　than　solid　parts。　　But　if　there　be　four　such　degrees　of　particles；　the　least　of　which　are　solid；　the　body　will　have　fifteen　times　more　pores　than　solid　parts。　　If　there　be　five　degrees；　the　body　will　have　one　and　thirty　times　more　pores　than　solid　parts。　　If　six　degrees；　the　body　will　have　sixty　an