darwin and modern science-第105节

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him　at　Down。　　In　the　postscript　of　a　letter　（of　April　15；　1880）　arranging　one　of　these　visits；　he　writes：　　〃Since　poor；　dear　Lyell's　death；　I　rarely　have　the　pleasure　of　geological　talk　with　anyone。〃）

In　one　of　the　very　interesting　conversations　which　I　had　with　Charles　Darwin　during　the　last　seven　years　of　his　life；　he　asked　me　in　a　very　pointed　manner　if　I　were　able　to　recall　the　circumstances；　accidental　or　otherwise；　which　had　led　me　to　devote　myself　to　geological　studies。　　He　informed　me　that　he　was　making　similar　inquiries　of　other　friends；　and　I　gathered　from　what　he　said　that　he　contemplated　at　that　time　a　study　of　the　causes　producing　SCIENTIFIC　BIAS　in　individual　minds。　　I　have　no　means　of　knowing　how　far　this　project　ever　assumed　anything　like　concrete　form；　but　certain　it　is　that　Darwin　himself　often　indulged　in　the　processes　of　mental　introspection　and　analysis；　and　he　has　thus　fortunately　left　usin　his　fragments　of　autobiography　and　in　his　correspondencethe　materials　from　which　may　be　reconstructed　a　fairly　complete　history　of　his　own　mental　development。

There　are　two　perfectly　distinct　inquiries　which　we　have　to　undertake　in　connection　with　the　development　of　Darwin's　ideas　on　the　subject　of　evolution：

FIRST。　　How；　when；　and　under　what　conditions　was　Darwin　led　to　a　conviction　that　species　were　not　immutable；　but　were　derived　from　pre…existing　forms？

SECONDLY。　　By　what　lines　of　reasoning　and　research　was　he　brought　to　regard　〃natural　selection〃　as　a　vera　causa　in　the　process　of　evolution？

It　is　the　first　of　these　inquiries　which　specially　interests　the　geologist；　though　geology　undoubtedly　played　a　partand　by　no　means　an　insignificant　partin　respect　to　the　second　inquiry。

When；　indeed；　the　history　comes　to　be　written　of　that　great　revolution　of　thought　in　the　nineteenth　century；　by　which　the　doctrine　of　evolution；　from　being　the　dream　of　poets　and　visionaries；　gradually　grew　to　be　the　accepted　creed　of　naturalists；　the　paramount　influence　exerted　by　the　infant　science　of　geologyand　especially　that　resulting　from　the　publication　of　Lyell's　epoch…making　work；　the　〃Principles　of　Geology〃cannot　fail　to　be　regarded　as　one　of　the　leading　factors。　　Herbert　Spencer　in　his　〃Autobiography〃　bears　testimony　to　the　effect　produced　on　his　mind　by　the　recently　published　〃Principles〃；　when；　at　the　age　of　twenty；　he　had　already　begun　to　speculate　on　the　subject　of　evolution　（Herbert　Spencer's　〃Autobiography〃；　London；　1904；　Vol。　I。　pages　175…177。）；　and　Alfred　Russel　Wallace　is　scarcely　less　emphatic　concerning　the　part　played　by　Lyell's　teaching　in　his　scientific　education。　　（See　〃My　Life；　a　record　of　Events　and　Opinions〃；　London；　1905；　Vol。　I。　page　355；　etc。　　Also　his　review　of　Lyell's　〃Principles〃　in　〃Quarterly　Review〃　（Vol。　126）；　1869；　pages　359…394。　　See　also　〃The　Darwin…Wallace　Celebration　by　the　Linnean　Society〃　（1909）；　page　118。）　　Huxley　wrote　in　1887　〃I　owe　more　than　I　can　tell　to　the　careful　study　of　the　〃Principles　of　Geology〃　in　my　young　days。〃　　（〃Science　and　Pseudo　Science〃；　〃Collected　Essays〃；　London；　1902；　Vol。　V。　page　101。）　　As　for　Charles　Darwin；　he　never　tiredeither　in　his　published　writings；　his　private　correspondence　or　his　most　intimate　conversationsof　ascribing　the　awakening　of　his　enthusiasm　and　the　direction　of　his　energies　towards　the　elucidation　of　the　problem　of　development　to　the　〃Principles　of　Geology〃　and　the　personal　influence　of　its　author。　　Huxley　has　well　expressed　what　the　author　of　the　〃Origin　of　Species〃　so　constantly　insisted　upon；　in　the　statements　〃Darwin's　greatest　work　is　the　outcome　of　the　unflinching　application　to　Biology　of　the　leading　idea　and　the　method　applied　in　the　〃Principles〃　to　Geology　（〃Proc。　Roy。　Soc。〃　Vol。　XLIV。　（1888）；　page　viii。；　〃Collected　Essays〃　II。　page　268；　1902。）；　and　〃Lyell；　for　others；　as　for　myself；　was　the　chief　agent　in　smoothing　the　road　for　Darwin。〃　　（〃Life　and　Letters　of　Charles　Darwin〃　II。　page　190。）

We　propose　therefore　to　consider；　first；　what　Darwin　owed　to　geology　and　its　cultivators；　and　in　the　second　place　how　he　was　able　in　the　end　so　fully　to　pay　a　great　debt　which　he　never　failed　to　acknowledge。　　Thanks　to　the　invaluable　materials　contained　in　the　〃Life　and　Letters　of　Charles　Darwin〃　（3　vols。）　published　by　Mr　Francis　Darwin　in　1887；　and　to　〃More　Letters　of　Charles　Darwin〃　（2　vols。）　issued　by　the　same　author；　in　conjunction　with　Professor　A。C。　Seward；　in　1903；　we　are　permitted　to　follow　the　various　movements　in　Darwin's　mind；　and　are　able　to　record　the　story　almost　entirely　in　his　own　words。　　（The　first　of　these　works　is　indicated　in　the　following　pages　by　the　letters　〃L。L。〃；　the　second　by　〃M。L。〃）

From　the　point　of　view　of　the　geologist；　Darwin's　life　naturally　divides　itself　into　four　periods。　　In　the　first；　covering　twenty…two　years；　various　influences　were　at　work　militating；　now　for　and　now　against；　his　adoption　of　a　geological　career；　in　the　second　periodthe　five　memorable　years　of　the　voyage　of　the　〃Beagle〃the　ardent　sportsman　with　some　natural…history　tastes；　gradually　became　the　most　enthusiastic　and　enlightened　of　geologists；　in　the　third　period；　lasting　ten　years；　the　valuable　geological　recruit　devoted　nearly　all　his　energies　and　time　to　geological　study　and　discussion　and　to　preparing　for　publication　the　numerous　observations　made　by　him　during　the　voyage；　the　fourth　period；　which　covers　the　latter　half　of　his　life；　found　Darwin　gradually　drawn　more　and　more　from　geological　to　biological　studies；　though　always　retaining　the　deepest　interest　in　the　progress　and　fortunes　of　his　〃old　love。〃　　But　geologists　gladly　recognise　the　fact　that　Darwin　immeasurably　better　served　their　science　by　this　biological　work；　than　he　could　possibly　have　done　by　confining　himself　to　purely　geological　questions。

From　his　earliest　childhood；　Darwin　was　a　collector；　though　up　to　the　time　when；　at　eight　years　of　age；　he　went　to　a　preparatory　school；　seals；　franks　and　similar　trifles　appear　to　have　been　the　only　objects　of　his　quest。　　But　a　stone；　which　one　of　his　schoolfellows　at　that　time　gave　to　him；　seems　to　have　attracted　his　attention　and　set　him　seeking　for　pebbles　and　minerals；　as　the　result　of　this　newly　acquired　taste；　he　says　（writing　in　1838）　〃I　distinctly　recollect　the　desire　I　had　of　being　able　to　know　something　about　every　pebble　in　front　of　the　hall　doorit　was　my　earliest　and　only　geological　aspiration　at　that　time。〃　　（〃M。L。〃　I。　page　3。）　　He　further　suspects　that　while　at　Mr　Case's　school　〃I　do　not　remember　any　mental　pursuits　except　those　of　collecting　stones；〃　etc。。。〃I　was　born　a　naturalist。〃　　（〃M。L。〃　I。　page　4。）

The　court…yard　in　front　of　the　hall　door　at　the　Mount　House；　Darwin's　birthplace　and　the　home　of　his　childhood；　is　surrounded　by　beds　or　rockeries　on　which　lie　a　number　of　pebbles。　　Some　of　these　pebbles　（in　quite　recent　times　as　I　am　informed）　have　been　collected　to　form　a　〃cobbled〃　space　in　front　of　the　gate　in　the　outer　wall；　which　fronts　the　hall　door；　and　a　similar　〃cobbled　area；〃　there　is　reason　to　believe；　may　have　existed　in　Darwin's　childhood　before　the　door　itself。　　The　pebbles；　which　were　obtained　from　a　neighbouring　gravel…pit；　being　derived　from　the　glacial　drift；　exhibit　very　striking　differences　in　colour　and　form。　　It　was　probably　this　circumstance　which　awakened　in　the　child　his　love　of　observation　and　speculation。　　It　is　certainly　remarkable　that　〃aspirations〃　of　the　kind　should　have　arisen　in　the　mind　of　a　child　of　9　or　10！

When　he　went　to　Shrewsbury　School；　he　relates　〃I　continued　collecting　minerals　with　much　zeal；　but　quite　unscientifically；all　that　I　cared　about　was　a　new…NAMED　mineral；　and　I　hardly　attempted　to　classify　them。〃　　（〃L。L。〃　I。　page　34。）

There　has　stood　from　very　early　times　in　Darwin's　native　town　of　Shrewsbury；　a　very　notable　boulder　which　has　probably　marked　a　boundary　and　is　known　as　the　〃Bell…stone〃giving　its　name　to　a　house　and　street。　　Darwin　tells　us　in　his　〃Autobiography〃　that　while　he　was　at　Shrewsbury　School　at　the　age　of　13　or　14　〃an　old　Mr　Cotton　in　Shropshire；　who　knew　a　good　deal　about　rocks〃　pointed　out　to　me　〃。。。the　'bell…stone'；　he　told　me　that　there　was　no　rock　of　the　same　kind　nearer　than　Cumberland　or　Scotland；　and　he　solemnly　assured　me　that　the　world　would　come　to　an　end　before　anyone　would　be　able　to　explain　how　this　stone　came　where　it　now　lay〃！　　Darwin　adds　〃This　produced　a　deep　impression　on　me；　and　I　meditated　over　this　wonderful　stone。〃　　（〃L。L。〃　I。　page　41。）

The　〃bell…stone〃　has　now；　owing　to　the　necessities　of　building；　been　removed　a　short　distance　from　its　original　site；　and　is　carefully　preserved　within　the　walls　of　a　bank。　　It　is　a　block　of　irregular　shape　3　feet　long　and　2　feet　wide；　and　about　1　foot　thick；　weighing　probably　not　less　than　one…third　of　a　ton。　　By　the　courtesy　of　the　directors　of　the　National　Provincial　Bank　of　England；　I　have　been　able　to　make　a　minute　examination　of　it；　and　Professors　Bonney　and　Watts；　with　Mr　Harker　and　Mr　Fearnsides　have　given　me　their　valuable　assistance。　　The　rock　is　a　much　altered　andesite　and　was　probably　derived　from　the　Arenig　district　in　North　Wales；　or　possibly　from　a　point　nearer　the　Welsh　Border。　　（I　am　greatly　indebted　to　the　Managers　of　the　Bank　at　Shrewsbury　for　kind　assistance　in　the　examinatio