thoughts on man-第68章

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　is　still　the　same；　when　my　business　is　merely　that　of　an　observer　and　a　traveller。　　I　know　water　from　earth；　land　from　sea；　and　mountains　from　vallies；　because　I　have　had　experience　of　these　objects；　and　confidently　infer　that；　when　certain　appearances　present　themselves　to　my　organs　of　sight；　I　shall　find　the　same　results　to　all　my　other　senses；　as　I　found　when　such　appearances　occurred　to　me　before。

But　the　interval　that　divides　the　objects　which　occur　upon　and　under　the　earth；　and　are　accessible　in　all　ways　to　our　examination；　on　the　one　hand；　and　the　lights　which　are　suspended　over　our　heads　in　the　heavens　on　the　other；　is　of　the　broadest　and　most　memorable　nature。　　Human　beings；　in　the　infancy　of　the　world；　were　contented　reverently　to　behold　these　in　their　calmness　and　beauty；　perhaps　to　worship　them；　and　to　remark　the　effects　that　they　produced；　or　seemed　to　produce；　upon　man　and　the　subjects　of　his　industry。　　But　they　did　not　aspire　to　measure　their　dimensions；　to　enquire　into　their　internal　frame；　or　to　explain　the　uses；　far　removed　from　our　sphere　of　existence；　which　they　might　be　intended　to　serve。

It　is　however　one　of　the　effects　of　the　improvement　of　our　intellect；　to　enlarge　our　curiosity。　　The　daringness　of　human　enterprise　is　one　of　the　prime　glories　of　our　nature。　　It　is　our　boast　that　we　undertake　to　〃measure　earth；　weigh　air；　and　state　the　tides。〃　　And；　when　success　crowns　the　boldness　of　our　aspirations　after　what　vulgar　and　timorous　prudence　had　pronounced　impossible；　it　is　then　chiefly　that　we　are　seen　to　participate　of　an　essence　divine。

What　has　not　man　effected　by　the　boldness　of　his　conceptions　and　the　adventurousness　of　his　spirit？　　The　achievements　of　human　genius　have　appeared　so　incredible；　till　they　were　thoroughly　examined；　and　slowly　established　their　right　to　general　acceptance；　that　the　great　heroes　of　intellect　were　universally　regarded　by　their　contemporaries　as　dealers　in　magic；　and　implements　of　the　devil。　　The　inventor　of　the　art　of　printing；　that　glorious　instrument　for　advancing　the　march　of　human　improvement；　and　the　discoverer　of　the　more　questionable　art　of　making　gunpowder；　alike　suffered　under　this　imputation。　　We　have　rendered　the　seas　and　the　winds　instruments　of　our　pleasure；　〃exhausted　the　old　world；　and　then　discovered　a　new　one；〃　have　drawn　down　lightning　from　heaven；　and　exhibited　equal　rights　and　independence　to　mankind。　　Still　however　it　is　incumbent　on　us　to　be　no　less　wary　and　suspicious　than　we　are　bold；　and　not　to　imagine；　because　we　have　done　much；　that　we　are　therefore　able　to　effect　every　thing。

As　was　stated　in　the　commencement　of　this　Essay；　we　know　our　own　sensations；　and　we　know　little　more。　　Matter；　whether　in　its　primary　or　secondary　qualities；　is　certainly　not　the　sort　of　thing　the　vulgar　imagine　it　to　be。　　The　illustrious　Berkeley　has　taught　many　to　doubt　of　its　existence　altogether；　and　later　theorists　have　gone　farther　than　this；　and　endeavoured　to　shew；　that　each　man；　himself　while　he　speaks　on　the　subject；　and　you　and　I　while　we　hear；　have　no　conclusive　evidence　to　convince　us；　that　we　may　not；　each　of　us；　for　aught　we　know；　be　the　only　thing　that　exists；　an　entire　universe　to　ourselves。

We　will　not　however　follow　these　ingenious　persons　to　the　startling　extreme　to　which　their　speculations　would　lead　us。　　But；　without　doing　so；　it　will　not　misbecome　us　to　be　cautious；　and　to　reflect　what　we　do；　before　we　take　a　leap　into　illimitable　space。


SECTION　II。

〃The　sun；〃　we　are　told；　〃is　a　solid　body；　ninety…five　millions　of　miles　distant　from　the　earth　we　inhabit；　one　million　times　larger　in　cubic　measurement；　and　to　such　a　degree　impregnated　with　heat；　that　a　comet；　approaching　to　it　within　a　certain　distance；　was　by　that　approximation　raised　to　a　heat　two　thousand　times　greater　than　that　of　red…hot　iron。〃

It　will　be　acknowledged；　that　there　is　in　this　statement　much　to　believe；　and　we　shall　not　be　exposed　to　reasonable　blame；　if　we　refuse　to　subscribe　to　it；　till　we　have　received　irresistible　evidence　of　its　truth。

It　has　already　been　observed；　that；　for　the　greater　part　of　what　we　imagine　we　know　on　the　surface　or　in　the　bowels　of　the　earth；　we　have；　or　may　have　if　we　please；　the　evidence　of　more　than　one　of　our　senses；　combining　to　lead　to　the　same　conclusion。　　For　the　propositions　of　astronomy　we　have　no　sensible　evidence；　but　that　of　sight；　and　an　imperfect　analogy；　leading　from　those　visible　impressions　which　we　can　verify；　to　a　reliance　upon　those　which　we　cannot。

The　first　cardinal　particular　we　meet　with　in　the　above　statement　concerning　the　sun；　is　the　term；　distance。　　Now；　all　that；　strictly　speaking；　we　can　affirm　respecting　the　sun　and　other　heavenly　bodies；　is　that　we　have　the　same　series　of　impressions　respecting　them；　that　we　have　respecting　terrestrial　objects　near　or　remote；　and　that　there　is　an　imperfect　analogy　between　the　one　case　and　the　other。

Before　we　affirm　any　thing；　as　of　our　own　knowledge　and　competence；　respecting　heavenly　bodies　which　are　said　to　be　millions　of　millions　of　miles　removed　from　us；　it　would　not　perhaps　be　amiss　that　we　should　possess　ourselves　of　a　certain　degree　of　incontestible　information；　as　to　the　things　which　exist　on　the　earth　we　inhabit。　　Among　these；　one　of　the　subjects　attended　with　a　great　degree　of　doubt　and　obscurity；　is　the　height　of　the　mountains　with　which　the　surface　of　the　globe　we　inhabit　is　diversified。　　It　is　affirmed　in　the　received　books　of　elementary　geography；　that　the　Andes　are　the　highest　mountains　in　the　world。　　Morse；　in　his　American　Gazetteer；　third　edition；　printed　at　Boston　in　1810＇46＇；　says；　〃The　height　of　Chimborazzo；　the　most　elevated　point　of　the　vast　chain　of　the　Andes；　is　20；280　feet　above　the　level　of　the　sea；　which　is　7102　feet　higher　than　any　other　mountain　in　the　known　world：〃　thus　making　the　elevation　of　the　mountains　of　Thibet；　or　whatever　other　rising　ground　the　compiler　had　in　his　thought；　precisely　13；178　feet　above　the　level　of　the　sea；　and　no　more。　　This　decision　however　has　lately　been　contradicted。　　Mr。　Hugh　Murray；　in　an　Account　of　Discoveries　and　Travels　in　Asia；　published　in　1820；　has　collated　the　reports　of　various　recent　travellers　in　central　Asia；　and　he　states　the　height　of　Chumularee；　which　he　speaks　of　as　the　most　elevated　point　of　the　mountains　of　Thibet；　as　nearly　30；000　feet　above　the　level　of　the　sea。

＇46＇　Article；　Andes。


The　elevation　of　mountains；　till　lately；　was　in　no　way　attempted　to　be　ascertained　but　by　the　use　of　the　quadrant）　and　their　height　was　so　generally　exaggerated；　that　Riccioli；　one　of　the　most　eminent　astronomers　of　the　seventeenth　century；　gives　it　as　his　opinion　that　mountains；　like　the　Caucasus；　may　have　a　perpendicular　elevation　of　fifty　Italian　miles＇47＇。　　Later　observers　have　undertaken　to　correct　the　inaccuracy　of　these　results　through　the　application　of　the　barometer；　and　thus；　by　informing　themselves　of　the　weight　of　the　air　at　a　certain　elevation；　proceeding　to　infer　the　height　of　the　situation。

＇47＇　Rees；　Encyclopedia；　article；　Mountains。


There　are　many　circumstances；　which　are　calculated　to　induce　a　circumspect　enquirer　to　regard　the　affirmative　positions　of　astronomy；　as　they　are　delivered　by　the　most　approved　modern　writers；　with　considerable　diffidence。

They　are　founded；　as　has　already　been　said；　next　to　the　evidence　of　our　senses；　upon　the　deductions　of　mathematical　knowledge。

Mathematics　are　either　pure　or　mixed。

Pure　mathematics　are　concerned　only　with　abstract　propositions；　and　have　nothing　to　do　with　the　realities　of　nature。　　There　is　no　such　thing　in　actual　existence　as　a　mathematical　point；　line　or　surface。　　There　is　no　such　thing　as　a　circle　or　square。　　But　that　is　of　no　consequence。　　We　can　define　them　in　words；　and　reason　about　them。　　We　can　draw　a　diagram；　and　suppose　that　line　to　be　straight　which　is　not　really　straight；　and　that　figure　to　be　a　circle　which　is　not　strictly　a　circle。　　It　is　conceived　therefore　by　the　generality　of　observers；　that　mathematics　is　the　science　of　certainty。

But　this　is　not　strictly　the　case。　　Mathematics　are　like　those　abstract　and　imaginary　existences　about　which　they　are　conversant。　　They　may　constitute　in　themselves；　and　i