thoughts on man-第52章

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And　yet；　from　this　small　postulate；　the　astronomers　proceed　to　deduce　the　most　astounding　conclusions。　　They　tell　us；　that　the　distance　of　the　nearest　fixed　star　from　the　earth　is　at　least　7；600；000；000；000　miles；　and　of　another　they　name；　not　less　than　38　millions　of　millions　of　miles。　　A　cannon…ball　therefore；　proceeding　at　the　rate　of　about　twenty　miles　in　a　minute　would　be　760；000　years　in　passing　from　us　to　the　nearest　fixed　star；　and　3；800；000　in　passing　to　the　second　star　of　which　we　speak。　　Huygens　accordingly　concluded；　that　it　was　not　impossible；　that　there　might　be　stars　at　such　inconceivable　distances　from　us；　that　their　light　has　not　yet　reached　the　earth　since　its　creation＇61＇。

＇61＇　Ibid；　p。　408。


The　received　system　of　the　universe；　founded　upon　these　so　called　discoveries；　is　that　each　of　the　stars　is　a　sun；　having　planets　and　comets　revolving　round　it；　as　our　sun　has　the　earth　and　other　planets　revolving　round　him。　　It　has　been　found　also　by　the　successive　observations　of　astronomers；　that　a　star　now　and　then　is　totally　lost；　and　that　a　new　star　makes　its　appearance　which　had　never　been　remarked　before：　　and　this　they　explain　into　the　creation　of　a　new　system　from　time　to　time　by　the　Almighty　author　of　the　universe；　and　the　destruction　of　an　old　system　worn　out　with　age＇62＇。　　We　must　also　remember　the　power　of　attraction　every　where　diffused　through　infinite　space；　by　means　of　which；　as　Herschel　assures　us；　in　great　length　of　time　a　nebula；　or　cluster　of　stars；　may　be　formed；　while　the　projectile　force　they　received　in　the　beginning　may　prevent　them　from　all　coming　together；　at　least　for　millions　of　ages。　　Some　of　these　nebulae；　he　adds；　cannot　well　be　supposed　to　be　at　a　less　distance　from　us　than　six　or　eight　thousand　times　the　distance　of　Sirius＇63＇。　　Kepler　however　denies　that　each　star；　of　those　which　distinctly　present　themselves　to　our　sight；　can　have　its　system　of　planets　as　our　sun　has；　and　considers　them　as　all　fixed　in　the　same　surface　or　sphere；　since；　if　one　of　them　were　twice　or　thrice　as　remote　as　another；　it　would；　supposing　their　real　magnitudes　to　be　equal；　appear　to　be　twice　or　thrice　as　small；　whereas　there　is　not　in　their　apparent　magnitudes　the　slightest　difference＇64＇。

＇62＇　Encycl。　Lond。　Vol。　II；　p。　411。

＇63＇　Ibid；　p。　348。

＇64＇　Ibid；　p。　411。


Certainly　the　astronomers　are　a　very　fortunate　and　privileged　race　of　men；　who　talk　to　us　in　this　oracular　way　of　〃the　unseen　things　of　God　from　the　creation　of　the　world；〃　hanging　up　their　conclusions　upon　invisible　hooks；　while　the　rest　of　mankind　sit　listening　gravely　to　their　responses；　and　unreservedly　〃acknowledging　that　their　science　is　the　most　sublime；　the　most　interesting；　and　the　most　useful　of　all　the　sciences　cultivated　by　man＇65＇。〃

＇65＇　Ferguson；　Astronomy；　Section　1。


We　have　a　sensation；　which　we　call　the　sensation　of　distance。　　It　comes　to　us　from　our　sight　and　our　other　senses。　　It　does　not　come　immediately　by　the　organ　of　sight。　　It　has　been　proved；　that　the　objects　we　see；　previously　to　the　comparison　and　correction　of　the　reports　of　the　organ　of　sight　with　those　of　the　other　senses；　do　not　suggest　to　us　the　idea　of　distance；　but　that　on　the　contrary　whatever　we　see　seems　to　touch　the　eye；　even　as　the　objects　of　the　sense　of　feeling　touch　the　skin。

But；　in　proportion　as　we　compare　the　impressions　made　upon　our　organs　of　sight　with　the　impressions　made　on　the　other　senses；　we　come　gradually　to　connect　with　the　objects　we　see　the　idea　of　distance。　　I　put　out　my　hand；　and　find　at　first　that　an　object　of　my　sense　of　sight　is　not　within　the　reach　of　my　hand。　　I　put　out　my　hand　farther；　or　by　walking　advance　my　body　in　the　direction　of　the　object；　and　I　am　enabled　to　reach　it。　　From　smaller　experiments　I　proceed　to　greater。　　I　walk　towards　a　tree　or　a　building；　the　figure　of　which　presents　itself　to　my　eye；　but　which　I　find　upon　trial　to　have　been　far　from　me。　　I　travel　towards　a　place　that　I　cannot　see；　but　which　I　am　told　lies　in　a　certain　direction。　　I　arrive　at　the　place。　　It　is　thus；　that　by　repeated　experiments　I　acquire　the　idea　of　remote　distances。

To　confine　ourselves　however　to　the　question　of　objects；　which　without　change　of　place　I　can　discover　by　the　sense　of　sight。　　I　can　see　a　town；　a　tower；　a　mountain　at　a　considerable　distance。　　Let　us　suppose　that　the　limit　of　my　sight；　so　far　as　relates　to　objects　on　the　earth；　is　one　hundred　miles。　　I　can　travel　towards　such　an　object；　and　thus　ascertain　by　means　of　my　other　senses　what　is　its　real　distance。　　I　can　also　employ　certain　instruments；　invented　by　man；　to　measure　heights；　suppose　of　a　tower；　and；　by　experiments　made　in　ways　independent　of　these　instruments；　verify　or　otherwise　the　report　of　these　instruments。

The　height　of　the　Monument　of　London　is　something　more　than　two　hundred　feet。　　Other　elevations；　the　produce　of　human　labour；　are　considerably　higher。　　It　is　in　the　nature　of　the　mind；　that　we　conclude　from　the　observation　that　we　have　verified；　to　the　accuracy　of　another；　bearing　a　striking　analogy　to　the　former；　that　we　have　not　verified。　　But　analogy　has　its　limits。　　Is　it　of　irresistible　certainty；　or　is　it　in　fact　to　be　considered　as　approaching　to　certainty；　because　we　have　verified　an　observation　extending　to　several　hundred　feet；　that　an　observation　extending　to　ninety…five　millions　of　miles；　or　to　the　incredible　distances　of　which　Herschel　so　familiarly　talks；　is　to　be　treated　as　a　fact；　or　laid　down　as　a　principle　in　science？　　Is　it　reasonable　to　consider　two　propositions　as　analogous；　when　the　thing　affirmed　in　the　one　is　in　dimension　many　million　times　as　great　as　the　thing　affirmed　in　the　other？　　The　experience　we　have　had　as　to　the　truth　of　the　smaller；　does　it　authorise　us　to　consider　the　larger　as　unquestionable？　　That　which　I　see　with　a　bay　of　the　sea　or　a　wide　river　between；　though　it　may　appear　very　like　something　with　which　I　am　familiar　at　home；　do　I　immediately　affirm　it　to　be　of　the　same　species　and　nature；　or　do　I　not　regard　it　with　a　certain　degree　of　scepticism；　especially　if；　along　with　the　resemblance　in　some　points；　it　differs　essentially；　as　for　example　in　magnitude；　in　other　points？　　We　have　a　sensation；　and　we　enquire　into　its　cause。　　This　is　always　a　question　of　some　uncertainty。　　Is　its　cause　something　of　absolute　and　substantive　existence　without　me；　or　is　it　not？　　Is　its　cause　something　of　the　very　same　nature；　as　the　thing　that　gave　me　a　similar　sensation　in　a　matter　of　comparatively　a　pigmy　and　diminutive　extension？

All　these　questions　an　untrained　and　inquisitive　mind　will　ask　itself　in　the　propositions　of　astronomy。　　We　must　believe　or　not；　as　we　think　proper　or　reasonable。　　We　have　no　way　of　verifying　the　propositions　by　the　trial　of　our　senses。　　There　they　lie；　to　be　received　by　us　in　the　construction　that　first　suggests　itself　to　us；　or　not。　　They　are　something　like　an　agreeable　imagination　or　fiction：　　and　a　sober　observer；　in　cold　blood；　will　be　disposed　deliberately　to　weigh　both　sides　of　the　question；　and　to　judge　whether　the　probability　lies　in　favour　of　the　actual　affirmation　of　the　millions　of　millions　of　miles；　and　the　other　incredible　propositions　of　the　travelling　of　light；　and　the　rest；　which　even　the　most　cautious　and　sceptical　of　the　retainers　of　modern　astronomy；　find　themselves　compelled　to　receive。

But　I　shall　be　told；　that　the　results　of　our　observations　of　the　distances　of　the　heavenly　bodies　are　unvaried。　　We　have　measured　the　distances　and　other　phenomena　of　the　sun；　the　moon；　Mercury；　Venus；　Mars；　Jupiter；　Saturn；　and　their　satellites；　and　they　all　fall　into　a　grand　system；　so　as　to　convey　to　every　unprejudiced　mind　the　conviction　that　this　system　is　the　truth　itself。　　If　we　look　at　them　day　after　day；　and　year　after　year；　we　see　them　for　ever　the　same；　and　performing　the　same　divine　harmony。　　Successive　astronomers　in　different　ages　and　countries　have　observed　the　celestial　orbs；　and　swept　the　heavens；　and　for　ever　bring　us　back　the　same　story　of　the　number；　the　dimensions；　the　distances；　and　the　arrangement　of　the　heavenly　bodies　which　form　the　subject　of　astronomical　science。

This　we　have　seen　indeed　not　to　be　exactly　the　case。　　But；　if　it　were；　it　would　go　a　very　little　way　towards　proving　the　point　it　was　brought　to　prove。　　It　would　shew　that；　the　sensations　and　results　being　similar；　the　causes　of　those　results　must　be　similar　to　each　other；　but　it　would　not　shew　that　the　causes　were　similar　to　the　sensations　produced。　　Thus；　in　the　sensations　which　belong　to　taste；　smell；　sound；　colour；　and　to　those　of　heat　and　cold；　there　is　all　the　uniformity　which　would　arise；　when　the　real　external　causes　bore　the　most　exact　similitude　to　the　perceptions　they　generate；　and　yet　it　is　now　universally　confessed　that　tastes；　scents；　sounds；　colours；　and　heat　and　cold　do　not　exist　out　of　ourselves。　　All　that　we　are　entitled　therefore　to　conclude　as　to　the　magnitudes　and　distances　of　the　heavenly　bodies；　is；　that　the　causes　of　our　sensations　and　perceptions；　whatever　they　are；　are　not　less　uniform　than　the　sensations　and　perceptions　themselves。

It　is　further　alleged；　that　we　calculate　eclipses；　and　register　the　various　phenomena　of　the　heavenly　bodies。　　Thales　predicted　an　eclipse　of　the　sun；　which　took　place　nearly　six　hundred　years　before　the　Christian　era。　　The　Babylonians；　the　Persians；　the　Hindoos；　and　the　Chinese　early　turned　their　attention　to　astronomy。　　Many　of　their　observations　were　accurately　recorded；　and　their　tables　extend　to　a　period　of　three　thousand　years　before　the　birth　of　Christ。　　Does　not　all　this　strongly　argue　the　solidity　of　the　science　to　which　they　belong？　　Who；　after　this；　will　have　the　presumption　to　question；　that　the　men　who　profess　astronomy　proceed　on　real　grounds；　and　have　a　profound　knowledge　of　these　things；　which　at　first　sight　might　appear　to　be　set　at　a　distance　so　far　removed　from　our　ken？

The　answer　to　this　is　easy。　　I　believe　in　all　the　astronomy　that　was　believed　by　Thales。　　I　do　not　question　the　statements　relative　to　the　heavenly　bodies　that　were　delivered　by　the　wise　men　of　the　East。　　But　the　supposed　discoveries　that　were　made　in　the　eighteenth；　and　even　in　the　latter　part　of　the　seventeenth　century；　purporting　to　ascertain　the　precise　distance　of　the　sun；　the　planets；　and　even　of　the　fixed　stars；　are　matters　entirely　distinct　from　this。

Among　the　earliest　astronomers　of　Greece　were　Thales；　Anaximander；　Anaximenes　and　Anaxagoras。　　Thales；　we　are　told；　held　that　the　earth　is　a　sphere　or　globe；　Anaximenes　that　it　is　like　a　round；　flat　table；　Anaximander　that　the　sun　is　like　a　chariot…wheel；　and　is　twenty…eight　times　larger　than　the　earth。　　Anaxagoras　was　put　in　prison　for　affirming　that　the　sun　was　by　many　degrees　larger　than　the　whole　Peloponnesus＇66＇。　　Kepler　is　of　opinion　that　all　the　stars　are　at　an　equal　distance　from　us；　and　are　fixed　in　the　same　surface　or　sphere。

＇66＇　Plutarch；　De　Placitis　Philosophorum。　　Diogenes　Laertius。


In　reality　the　observations　and　the　facts　of　astronomy　do　not　depend　either　upon　the　magnitudes　or　the　distances　of　the　heavenly　bodies。　　They　proceed　in　the　first　place　upon　what　may　lie　seen　with　the　naked　eye。　　They　require　an　accurate　and　persevering　attention。　　They　may　be　assisted　by　telescopes